Merge pull request #202 from beaufortfrancois/master

Added support for progress notifications
Remove cca code for adding and removing XWalk library
Correct URL manipulation methods for data urls (Fixes #201)
Update RELEASENOTES.md
ios: Close open sockets on app reset/shutdown (Fixes #203)
Update RELEASENOTES with correct crosswalk opt-out
ios: Don't remove sockets from dictionary while iterating over it
Fixed an NPE when getting an app id.

If an app had no manifest, we tried to access it anyway.
Added our DevByte to the README.
Update cordova-android, cordova-crosswalk-engine, google-play-services
Added a screenshot for the IO Byte.
Changed the DevByte link to an image link.
Updated for release 2.1
Set version to 0.2.1-rc1.
fixed 0.2.1 release notes
Fix #209: Tell curl to follow redirects
Update config xml right after cca create
Set version to 0.2.1