Use the require.js optimizer

Use django-require to bundle Widgy's js during collectstatic.

`widgy-main.js` is a stub that gets turned into the widgy js bundle
during collectstatic. This allows us to always include it during
development. Since it doesn't do anything, require.js will work as
normal (lazily loading everything), until the bundle gets built.
Fix css paths to make it work with CachedStaticFilesStorage
cachebust require.js in development
Youtube video IDs can have dashes

See https://groups.google.com/forum/#!topic/youtube-api-gdata/maM-h-zKPZc
Merge branch 'require'

* require:
  cachebust require.js in development
  Fix css paths to make it work with CachedStaticFilesStorage
  Use the require.js optimizer
Use CKEditor instead of Markdown/Pagedown for email content

  - Markdown widget is deprecated
  - Clients want HTML, not markdown

For plaintext email clients, we use html2text to convert the HTML to
markdown. This patch is backwards compatible, because it converts all
the existing markdown to HTML in the migration.
Add an 'include_form_data' option to EmailSuccessHandlers

This allows the data from the form submission to be included in the
success email.
Fix error when `to_ident` is blank in a EmailUserHandler

We need to handle the case where the form is submitted before the
EmailUserHandler is ready.
Added staticfiles