Add explicit wait to JS transcript tests

Cheatsheet modal is accessible. LMS-1303

Add css mode to the compressed file.

Commit/rollback transaction after rendering response to prevent TransactionManagementErrors due to db access in templates.

Fix for static path parsing

Use the leanModal stuff to show the cheatsheet dialog in the wiki.

LMS-1303

When a url contains a query parameter it gets incorrectly parsed
when replacing the /static portion.

This fix handles urls with query parameters.

STUD-833

test bucket existence before creation

Prevent unbounded nesting of lms field_datas

Previously, whenever a XModule was created from a XDescriptor, we
created another level of nesting of FieldData objects. This change
prevents that nesting.

[TKTS-393]

Also let xml import work on modulestores that don't use write signaling

student.views.confirm_email_change: commit/rollback transaction after rendering response instead of before

student.tests: Added db access in mock_render_to_response() to test any issues with @transaction.commit_manually

Add masked input back into RequireJS

Add skip links to both CMS and LMS

Bug: LMS-1311

LMS-1311

LMS-1311

* add HTML for links
* hide links when they are not focused
* when focused, show link (as recommended)
* move accessibility tools to common

LMS-1311

Upgrade newrelic so that we can use the new histogram and percentile features

Update URLs for assets

Added explicit wait to failing JS test

A11Y changes: better :focus styling, increased contrast, and added image alt texts

- Doubled up :hover and :focus styling to improve a11y
- Increase contrast of certain UI elements for improved a11y
- Added some image alt text for a11y
- Changed video caption styling to blue and made them underline on hover and added a skip link before video for screenreaders.

Fixes Bugs:
- LMS-1336

Certificates: Add regeneration command

Pull modal cover and date utils into their own files.

Convert course team management to new URL scheme.