Named `FormulaEquationInput` (name up for debate)

- Based off ChemEqnIn
- Add FormulaEquationInput in inputtypes.py
- Add a call to a skeleton method for a preview

javascript:

- Queue up some MathJax
- Put some ordering on the AJAX requests: add a parameter when the request was started, when it returns check that it isn't outdated before displaying the preview
- Tests

Note: we moved the `jsinput` tests and DISABLED them, because they were causing the tests to fail.

This resolves an error that would sometimes occur on Mac OS X:
"Error: EMFILE, too many open files"

    From PR review.

Instead, we use XModule field default values when creating an empty
XModule. Driven by this use case, we also allow for XModules to be
created in memory without being persisted to the database at all. This
necessitates a change to the Modulestore api, replacing clone_item with
create_draft and save_xmodule.

This explains why acceptance_static is used

Acceptance_static is used to prevent collect static from using a seed
test.py had its seed removed due to redundancy

Windows doesn't differentiate between files with/without executable bit,
so this can't be used to exclude the README file from the migrations to
be executed, when the sources are accessed from a Windows partition.

Split components with : instead of _

This allows the build to pass in Jenkins

This ensures that `rake test` will clean the report directories
*before* running the JS tests.

This allows the build to pass in Jenkins

This ensures that `rake test` will clean the report directories
*before* running the JS tests.

directory is created before it is cleaned.

Added test cleaning to fasttest_* instead of test_*, so that
it always gets executed for lms and cms tests.

Added comment to `directory` command for tests.rake

Separated cleaning of test fixtures from cleaning of reports
directory to resolve conflicts with collectstatic.

Previously, multiple copies of the watchers started from the different
shells would run simultaneously, which left the possiblity of zombie
watchers, increased resource consumption, and incorrect results. This
fixes that problem by only starting a watcher if that same command isn't
already in the process list.

Fixes LMS-499

When running under watchmedo, coffee doesn't display any useful
information when it recompiles a changed file, so we make watchmedo echo
that information instead.

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.

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.