Add DemoExpress wiki
 Edited language. snapshot w/transparency.

 Edited some wording.  Added transparency behind snapshot image.
Merge branch 'add-demoexpress-wiki'
 Fixed block on cordova migrate pg, fixed title

 Fixed a missing code block on the "migrate an existing cordova" pg.
 Fixed title of home screen
Merge branch 'pre-code-missing'
 Added analytics string to home page video

 As requested, added "enablejsapi=1" in the video string
for the Google I/O video on the home page so that the analytics
measuring guys could tell us how many times it was viewed and for how
long.