Separate verification deadline from upgrade deadline

* Add verification deadline model.
* Populate verification deadlines from course modes table.
* Update student dashboard to use verification deadlines.
* Update pay-and-verify view to use verification deadlines.
* Simplify Django admin for course modes and add validation.
* Add verification deadline to Django admin for course modes.
* Add UI for when the upgrade deadline is missed in the pay-and-verify flow.

common/djangoapps/student/tests/test_verification_status.py

@@ -20,7 +20,7 @@ from xmodule.modulestore.tests.factories import CourseFactory
 from xmodule.modulestore.tests.django_utils import ModuleStoreTestCase
 from student.tests.factories import UserFactory, CourseEnrollmentFactory
 from course_modes.tests.factories import CourseModeFactory
-from verify_student.models import SoftwareSecurePhotoVerification  # pylint: disable=import-error
+from verify_student.models import VerificationDeadline, SoftwareSecurePhotoVerification  # pylint: disable=import-error
 from util.testing import UrlResetMixin
 
 
@@ -61,9 +61,11 @@ class TestCourseVerificationStatus(UrlResetMixin, ModuleStoreTestCase):
             mode="verified"
         )
 
-        # The default course has no verified mode,
-        # so no verification status should be displayed
-        self._assert_course_verification_status(None)
+        # Continue to show the student as needing to verify.
+        # The student is enrolled as verified, so we might as well let them
+        # complete verification.  We'd need to change their enrollment mode
+        # anyway to ensure that the student is issued the correct kind of certificate.
+        self._assert_course_verification_status(VERIFY_STATUS_NEED_TO_VERIFY)
 
     def test_need_to_verify_no_expiration(self):
         self._setup_mode_and_enrollment(None, "verified")
@@ -285,6 +287,7 @@ class TestCourseVerificationStatus(UrlResetMixin, ModuleStoreTestCase):
             user=self.user,
             mode=enrollment_mode
         )
+        VerificationDeadline.set_deadline(self.course.id, deadline)
 
     BANNER_ALT_MESSAGES = {
         None: "Honor",