Added testing for grading settings

Please note that 2 tests will not reliably work:
Deleting a grade- Was able to circumvent this with javascript
Moving the grade slider- Could not circumvent, is skipped but the framework is in place
Added in the drag and drop support
Merge branch 'master' into jonahstanley/add-gradingsettings-tests
Fixed click to comply to new css_click
On marketing site, disable course settings options that do not work.

When on the marketing site (edx.org) disable portions of the course settings page in Studio that do not actually work in that environment.
Don't concatenate together multiple strings.
pep8 fixes.
studio - revises markup/content for course about mgmt notices
studio - adds in basic rules for notices UI
studio - revises notice headings to use icons
Studio - adds minor UI/content changes to settings notices
Combined video and videoalpha acceptance tests.
Resolved conflict between two steps with the same name.
Fixed incorrect videoalpha template name
Changed videoalpha stub to exclude video sources, but include
the rest of the player.
Changed stubbing behavior in video templates to exclude
only the sources (not the player)
Updated video alpha template name to reflect recent changes in master.
Use built-in rakelibdir feature

Rake by default imports all .rake files in the rakelib dir, so we can
use that rather than doing our own import loop.
Provide instructions of ruby imports fail in rake

`rake install_prereqs` requires a minimal level of ruby and rake already
installed. If it doesn't exist, then print out a helpful message
indicating next steps.
Add system and env arguments to asset tasks

The preprocess task requires system and env arguments in order to
correctly load up the django environment to preprocess sass files to
inject themes.

In order for that task to recieve the arguments, all tasks that depend
on it also have to accept that same set of arguments.

This will all go away once the next evolution of themes arrives, which
will remove the preprocessing needed to inject theme names.
Switch to standard coffee watcher

Using `ulimit -n` to set the limit much higher than the default of 256
in Darwin seems to avoid the `EMFILE` error that was plaguing our Mac
developers.