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

Updates copy used in the checkbox label, constructs strings within the view instead of passing through a separate context variable, and alleviates unipain

Includes tests checking that the student views integrate with the profile API as expected.

Feature flagged. Puts a checkbox in the iframe. The iframe uses an organization_full_name parameter forwarded from Drupal by the courseware views and POSTs an email_opt_in parameter to the student views, preserving it on 403.

If a user is anonymous when they click the enroll button, they will automatically be enrolled in the course if they immediately log in our create an account.

Catch Exception instead of ValueError for accessing our general content cache -- exception thrown changed in django 1.4

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branch : cache_separation

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branch : cache_separation

Shift wiki and course.xml caching to use newly defined 'general' cache, separate from sessions left in 'default'

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branch : cache_separation