[WIP] Notes page.

@tymofij , @olmar , @jmclaus please review.

sandbox: http://polesye.m.sandbox.edx.org/courses/edX/DemoX/Demo_Course/edxnotes
> Why do we need to patch "edxnotes.views.get_notes" here? Seems it will not be used in edxnotes view.

Removed.