Two new certificate statuses are introduced, 'audit_passing' and
'audit_notpassing'. These signal that the GeneratedCertificate is not
to be displayed as a cert to the user, and that they either passed or
did not. This allows us to retain existing grading logic, as well as
maintaining correctness in analytics and reporting.

Ineligible certificates are hidden by using the
`eligible_certificates` manager on GeneratedCertificate. Some places
in the coe (largely reporting, analytics, and management commands) use
the default `objects` manager, since they need access to all
certificates.

ECOM-3040
ECOM-3515

This reverts commit 60860e3a.

An `eligible_for_certificate` field is added to the
GeneratedCertificate model. This way we can retain existing grading
logic, as well as maintaining correctness in analytics and reporting.

Ineligible certificates are hidden by using the
`eligible_certificates` manager on GeneratedCertificate. Some places
in the coe (largely reporting, analytics, and management commands) use
the default `objects` manager, since they need access to all
certificates.

This commit also updates the DB cache for acceptance tests.

* Add new role for support staff.
* Move dashboard/support functionality into a new Django app called "support".
* Add support view for searching and regenerating certificates.
* Refactor certificates views into separate files.