Switch from Rake to Paver
Change `if not args.skip_collect` to `if args.collect`

Simpler and clearer
from __future__ import print_function

and print errors and warnings to sys.stderr
write_stderr() function is unnecessary
Pull Paver requirements out into a separate file
Insert *right* at the front
Documentation for static page changes

STUD-1347
Merge pull request #3005 from singingwolfboy/db/paver

Paver v3
Merge pull request #2928 from edx/markhoeber/documentation/stud-1347

Documentation for changes to static pages
Help paver find the theme directory
Merge pull request #3075 from edx/db/paver-find-theme-dir

Help paver find the theme directory
xblock-external-ui: Add XBlock API call to render XBlock views
xblock-external-ui: Include CSRF token in the API answer
xblock-external-ui: Adds support for CORS headers (cross-domain request)