Paginate results of Courses API list endpoint

* Catalog results are now paginated
* Implements the new namespaced pagination described at
  https://openedx.atlassian.net/wiki/pages/viewpage.action?pageId=47481813
* API level code returns pythonic business objects
* View layer performs serialize at the view layer
* Convert views to use DRF generic views
* Removes an unintentional authentication decorator that caused
  the detail endpoint to return a 401 for anonymous users

MA-1724

lms/djangoapps/course_api/tests/test_serializers.py

@@ -0,0 +1,67 @@
+"""
+Test data created by CourseSerializer
+"""
+
+from datetime import datetime
+
+from rest_framework.test import APIRequestFactory
+from rest_framework.request import Request
+
+from xmodule.modulestore.tests.django_utils import ModuleStoreTestCase
+from xmodule.course_module import DEFAULT_START_DATE
+
+from ..serializers import CourseSerializer
+from .mixins import CourseApiFactoryMixin
+
+
+class TestCourseSerializerFields(CourseApiFactoryMixin, ModuleStoreTestCase):
+    """
+    Test variations of start_date field responses
+    """
+
+    def setUp(self):
+        super(TestCourseSerializerFields, self).setUp()
+        self.staff_user = self.create_user('staff', is_staff=True)
+        self.honor_user = self.create_user('honor', is_staff=False)
+        self.request_factory = APIRequestFactory()
+
+    def _get_request(self, user=None):
+        """
+        Build a Request object for the specified user
+        """
+        if user is None:
+            user = self.honor_user
+        request = Request(self.request_factory.get('/'))
+        request.user = user
+        return request
+
+    def test_advertised_start(self):
+        course = self.create_course(
+            course=u'custom',
+            start=datetime(2015, 3, 15),
+            advertised_start=u'The Ides of March'
+        )
+        result = CourseSerializer(course, context={'request': self._get_request()}).data
+        self.assertEqual(result['course_id'], u'edX/custom/2012_Fall')
+        self.assertEqual(result['start_type'], u'string')
+        self.assertEqual(result['start_display'], u'The Ides of March')
+
+    def test_empty_start(self):
+        course = self.create_course(start=DEFAULT_START_DATE, course=u'custom')
+        result = CourseSerializer(course, context={'request': self._get_request()}).data
+        self.assertEqual(result['course_id'], u'edX/custom/2012_Fall')
+        self.assertEqual(result['start_type'], u'empty')
+        self.assertIsNone(result['start_display'])
+
+    def test_description(self):
+        course = self.create_course()
+        result = CourseSerializer(course, context={'request': self._get_request()}).data
+        self.assertEqual(result['description'], u'A course about toys.')
+
+    def test_blocks_url(self):
+        course = self.create_course()
+        result = CourseSerializer(course, context={'request': self._get_request()}).data
+        self.assertEqual(
+            result['blocks_url'],
+            u'http://testserver/api/courses/v1/blocks/?course_id=edX%2Ftoy%2F2012_Fall'
+        )