Fixed up description for slideshare unit test
547 - Hiding chatbar and line numbers for etherpad previews
Issue 547 - Refactor previews for collaborative docs.

Previews are now generated by retrieving the HTML from the API,
writing it to an html file and processing it with PhantomJS.

This speeds up preview generation significantly as we now no longer
need to join the pad on the actual etherpad instance and load
in all the assets.
Merged master in issue-547-remove-line-numbers-etherpad-previews
Added an HTML and CSS file for collaborative document previews.
Cleaned up JS doc and created constants for file locations in the collabdoc processor
Merge branch 'issue-547-remove-line-numbers-etherpad-previews' of git://github.com/simong/Hilary into issue-547-remove-line-numbers-etherpad-previews
Improve preview visuals + documentation