Skip tilde files when importing

fix tests that were breaking on dev envs due to TIME_ZONE='UTC'

Avoid requesting unnecessary thread responses

Remove warning about LTI not working in Preview mode

Image Modal CMS HTML Block subtype

- Added YAML file for the HTML template code for the modal to work
- Added CSS and JS code for modal to look and function properly
- Updated code to take comments into account.
- Simplified HTML template and expanded JS to set up image modal on load.
- Added preliminary drag script.
- Converted jQuery UI draggable to Draggabilly

The front-end code for rendering a thread always makes an AJAX request
for the resopnses, regardless of how the thread was accessed (directly
by URL or by selecting it from the thread list). Previously, when
a user accessed a thread directly by URL, the LMS would initially
request the thread from the comments service with responses, but that
response data was never actually used. Now, the responses are not
fetched with that initial query.

Add acceptance tests for forum response pagination

Fix goto_position in sequence coffeescript.

Make i18n:generate more flexible

Sylvia/documentation/bld 801

Change order of tags (now alphabetical); add link list at beginning of document

Added an alt tag to the footer logo; added charset meta tag; moved

Add '' default to bodyclass in courseware templates

Prepend theme template paths

Jarv/db env override

Add periodic table and molecule editor to Additional Tools

Teach install-system-req.sh about `brew bundle`

make LMS accordion and progress datetime display respect settings.TIME_ZONE

Update i18n coding guidelines

fixup create-dev-env.sh

Make assets:coffee a dependency of i18n:extract

Minor test cleanup

It's not a constant, and some subclasses will want to make it a
function with @property.

Replace single-quotes with double-quotes so that #{@ajaxUrl} is
interpolated.