Some additional doc around all the functions in the front end.
We will want to flesh out the specifics of each Mixin, and associated UI models, as we complete each associated UI story.
Code Review changes.
Changing the if else in submission for clarity.
Deleting the base error in submissions mixin.
Merge pull request #42 from edx/sanchez/base_template_cleanup

Some additional doc around all the functions in the front end.