This centralizes the logic for group membership, and means that we
don't need to make queries to find out whether the legacy groups names exist.

Also includes some tests

Story: LMS-1127

Also includes some tests

Story: LMS-1127

add middleware to detect students with disabled accounts

add tests

migrations.

The most common error is Amazon SES having blacklisted an email address.
However, we handle any error being raised during user.email_user.

Fixes JIRA LMS-131

Django always returns string data from the database as unicode objects
(ref: https://docs.djangoproject.com/en/1.4/ref/unicode/#models).
Therefor, our factories should do the same

This allows specification of profile parameters when creating a user. Because
the profile contents are always accessed from the database, the user must be
saved to the database before the profile is created. This means that the
profile cannot be created if the user is merely being built (and not saved)
rather than created.

Changed constant to uppercase

using terrain.factories.py and capa.tests.response_xml_factory