Updated Tuskar README

A more descriptive Tuskar Overview based on the recently submitted
OpenStack Summit abstract.
Base documentation organization

* docs index page
   * links to wiki pages (until wiki pages are moved to docs)
   * TODO placeholders
   * text from updated README
   * link to demo video

(Ammended by jistr for .md -> .rst migration.)
Merge branch 'overview' into docs

Fixed line length in 'overview'

Conflicts:
	README.rst
Call ./docs/ documentation, not website
Merge pull request #95 from jistr/docs

Base documentation organization
Implements PUT /api/resource_classes/ID to update the Flavors

This will delete all existing flavors and replace them with those in the
PUT body. Addresses https://github.com/tuskar/tuskar/issues/50
Merge pull request #92 from marios/Issue50

Implements PUT /api/resource_classes/ID to update the Flavors