TNL-932: Add styling to Notes page.

TNL-932
@tymofij, @jmclaus, @clrux please review.

**sandbox:** http://tymofij.m.sandbox.edx.org/courses/edX/DemoX/Demo_Course/edxnotes/
> In that case, shouldn't we set templateText to an empty string to have the rest afterwards fail gracefully?

No, it's needed during development for ease understanding the problem and debugging. 
See, https://github.com/edx/edx-platform/blob/anton/edxnotes-apply-ui/cms/static/js/utils/templates.js