* mattdrayer: Add bulk checkout link to course views
* asadiqbal08: MAYN-225 replace the "Verify Now" button by the "Go to Dashboard" button in case of themed sites.
* mattdrayer: Add bulk_sku check in courseware.views

* mattdrayer: Add bulk checkout link to course views
* asadiqbal08: MAYN-225 replace the "Verify Now" button by the "Go to Dashboard" button in case of themed sites.
* mattdrayer: Add bulk_sku check in courseware.views

Add app_label definitions in Meta classes for models.
Move import of course_mode model into methods to prevent importing
the models at startup time.

Changing a field name in the way that we did (updating the Python
variable name and switching it to point to the old DB column) confuses
Django's migration autodetector. No DB changes are actually necessary,
but it thinks that a field has been removed and a new one added. This
means that Django will ask users to generate the migration it thinks
is necessary, which ended up with us dropping data. The fix is to run
the same migration on Django's internal model of the DB state, but not
actually touch the DB.

Please note that this is a squshed commit and the work of:
Symbolist, macdiesel, nedbat, doctoryes, muzaffaryousaf and muhammad-ammar

XCOM-94

added CoursmodeArchive model to save the old prices history

analytics -> instructor_analytics

analytics -> instructor_analytics

Added an expiration_datetime field to CourseModes, intended to eventually replace expiration_date.

Included relevant schema and data migration file.

LMS-1454