Entrance Exam authoring and messaging updates

Multi-commit history:
- hide drag functionality for entrance exam section.
- hide entrance exam subsection elements e.g. delete, drag, name etc.
- show unit/verticals expanded in case of entrance exam
- modify code in order to allow user to update entrance exam score from UI.
- write down unit tests.
- write down Jasmine tests.
- add bok-choy test
- updated bok-choy test
- internationalize string
- repositioned sequential block creatori
- SOL-221 (entrance exam message)
- SOL-199 LMS Part (show entrance exam content) and hide the course navigation bar.
- redirect the view in case of entrance exam.
- update code structure as per suggestions
- write down unit tests
- fix pep8
- instead of hiding the exam requirement message, now also showing the exam the completion message (success state).
- write down unit test to show exam completion message.
- Update code as per review suggestions
- update doc string
- addressed review suggestions
- change sequential message text
- css adjustments
- added new css class for entrance exam score in studio
- added Jasmine test for remaning coverage
- sequential message should appear under the context of entrance exam subsection.
- updated text in CMS and LMS as per suggestions.
- added unit text to insure sequential message should not be present in other chapters rather then entrance exam.
- skip setter if empty prerequisite course list
- exclude logic from xblock_info.js that is specifically related to entrance exam.
- added js tests and updated code as per suggestions
- added tests
- addressed several PR issues
- Several small fixes (style, refactoring)
- Fixed score update issue
- added some more unit tests.
- code suggested changes.
- addressed PR feedback

common/djangoapps/util/milestones_helpers.py

@@ -21,6 +21,8 @@ from milestones.api import (
     get_user_milestones,
 )
 from milestones.models import MilestoneRelationshipType
+from milestones.exceptions import InvalidMilestoneRelationshipTypeException
+from opaque_keys.edx.keys import UsageKey
 
 NAMESPACE_CHOICES = {
     'ENTRANCE_EXAM': 'entrance_exams'
@@ -150,6 +152,42 @@ def fulfill_course_milestone(course_key, user):
             add_user_milestone({'id': user.id}, milestone)
 
 
+def get_required_content(course, user):
+    """
+    Queries milestones subsystem to see if the specified course is gated on one or more milestones,
+    and if those milestones can be fulfilled via completion of a particular course content module
+    """
+    required_content = []
+    if settings.FEATURES.get('MILESTONES_APP', False):
+        # Get all of the outstanding milestones for this course, for this user
+        try:
+            milestone_paths = get_course_milestones_fulfillment_paths(
+                unicode(course.id),
+                serialize_user(user)
+            )
+        except InvalidMilestoneRelationshipTypeException:
+            return required_content
+
+        # For each outstanding milestone, see if this content is one of its fulfillment paths
+        for path_key in milestone_paths:
+            milestone_path = milestone_paths[path_key]
+            if milestone_path.get('content') and len(milestone_path['content']):
+                for content in milestone_path['content']:
+                    required_content.append(content)
+
+    #local imports to avoid circular reference
+    from student.models import EntranceExamConfiguration
+    can_skip_entrance_exam = EntranceExamConfiguration.user_can_skip_entrance_exam(user, course.id)
+    # check if required_content has any entrance exam and user is allowed to skip it
+    # then remove it from required content
+    if required_content and getattr(course, 'entrance_exam_enabled', False) and can_skip_entrance_exam:
+        descriptors = [modulestore().get_item(UsageKey.from_string(content)) for content in required_content]
+        entrance_exam_contents = [unicode(descriptor.location)
+                                  for descriptor in descriptors if descriptor.is_entrance_exam]
+        required_content = list(set(required_content) - set(entrance_exam_contents))
+    return required_content
+
+
 def calculate_entrance_exam_score(user, course_descriptor, exam_modules):
     """
     Calculates the score (percent) of the entrance exam using the provided modules

common/test/acceptance/tests/studio/test_studio_settings_details.py

@@ -162,3 +162,32 @@ class SettingsMilestonesTest(StudioCourseTest):
             css_selector='span.section-title',
             text='Entrance Exam'
         ))
+
+    def test_entrance_exam_has_unit_button(self):
+        """
+        Test that entrance exam should be created after checking the 'enable entrance exam' checkbox.
+        And user has option to add units only instead of any Subsection.
+        """
+        self.settings_detail.require_entrance_exam(required=True)
+        self.settings_detail.save_changes()
+
+        # getting the course outline page.
+        course_outline_page = CourseOutlinePage(
+            self.browser, self.course_info['org'], self.course_info['number'], self.course_info['run']
+        )
+        course_outline_page.visit()
+        course_outline_page.wait_for_ajax()
+
+        # button with text 'New Unit' should be present.
+        self.assertTrue(element_has_text(
+            page=course_outline_page,
+            css_selector='.add-item a.button-new',
+            text='New Unit'
+        ))
+
+        # button with text 'New Subsection' should not be present.
+        self.assertFalse(element_has_text(
+            page=course_outline_page,
+            css_selector='.add-item a.button-new',
+            text='New Subsection'
+        ))