Move Ajax scheduling UI tests to seltests.py
Fix some of the errors in Ajax scheduling backend tests

The tests were written when the change log was stored in memory.
Since then, the system has changed so that the change log is stored
in the database (AJAXChangeLog model) and is now accessed by index
rather than by time (see 04f6854).  This commit updates the tests to
match the new change log scheme.
(cherry picked from commit 6b957e68220f09bec0c31a18aedddeb6fd1fc834)

Conflicts:
	esp/esp/program/modules/tests/ajaxschedulingmodule.py
Correct CommPanelTest call of send_email_requests()
(cherry picked from commit 79621b12147bb52c2d6d24d5ffe8a3a3d77f7505)
Fix test failure in Ajax scheduling: testTooOldChangeLog

The test code was not actually doing anything after clearing the change log,
yet it expected that the view would request a reload.  In fact the view code
is smarter than that and only requests a reload if something has changed
since you deleted the change log.  So we have to test that behavior.
Fix StudentRegTest test_confirm()

This is the ProgramFrameworkTest flavor of the entertaining bug that
hit ProgramHappenTest (the "current school year" not being the current
year).  See d38afe9 and 1028cd3.
Remove esp.twilltests app

The code is 5+ years old and has not been used recently.  There are
now other tools for testing against a live server, which should not
be in our test suite, and we will have to come up with a better
solution for testing against a dev server running "in parallel"
with the test suite (like our Selenium tests).
Add a placeholder for the media dir checked by filebrowser tests
Stop trying to include/import twill
Fix theme tests

f4a3cae didn't work because {% comment %} does not appear in rendered
HTML.  Fix this by including the theme name in an HTML comment, but one
that is provided by elements/html in a reasonable place.