Aloha Editor + Spark sprint: token_filter fork on GitHub

For prototyping purposes, I have included a modified check_markup() function in the Edit module, so that we could experiment with "nested editables" (i.e. things that are editable *inside* the WYSIWYG editor). I've then modified the token_filter module so that the custom AE plug-in for editing tokens within the AE WYSIWYG would have the necessary API endpoints to call.

My modifications:
- https://github.com/wimleers/token_filter/commit/90a4f33dc73b0b48eac7472c...
- https://github.com/wimleers/token_filter/commit/deb17de7b167990b4f7a60e1...

The initial AE plug-in that was implemented by Tobias Steiner of Gentics/Aloha Editor:
- https://github.com/wimleers/token_filter/commit/232923a2a6ba615f2d4719f2...