Patch Release 2016-05-05

Release Candidate rc/2016-05-03

Moving main element up higher to not conflict with chart

Overriding display table-cell on instructor dashboard

Removing nav_skip block from template

Fix rc/2016-05-03 rebase with release branch

Jasmine has a global stack for creating a tree of specs. We need to load
spec files one by one, otherwise some end up getting nested under others.

This was fixed on the openedx dashboard, but missed on the edx.org theme
for the dashboard.

TNL-4366
Changes in studio to allow the hide_after_due setting to be utilized.

Includes:
    -python changes to contentstore, where the data is stored.
    -refactoring of timed-examination-preference-editor.underscore, to add this
        setting and make the editor more accessible.
    -javascript changes to link the new setting to the correct data model.
    -sass updates to fix a11y issues on the editor modal.
    -addition of post-due visibility information to course outline in studio.
    -new tests: python, js, acceptance, and a11y

Contains latest release, changes for TNL-4366

edxapp-migrate-lms figures out at system build time what databases
it needs to migrate (just default, or default + student_module_history).
This avoids paver needing to be clever about figuring out if a user has
enabled the split CSMHE databases flag and permits this to merge early
and safely.

We can turn the CSMHE flag on from configuration at the same time we
enable all of the database config and ensure that the new database is
created.  Until a devstack is provisioned using that version of
configuration, it'll continue to have 1 DB and migrate 1 DB.  This
allows us to better control deployment.

More accurately, this creates a 4th shard because the
last shard is always the default.

Revert "SUST-35 Implementation of course_key_from_string_or_404 to return course_key or raise a 404"

ECOM-4292

This supports a number of their new Error features.