push-guestbook: Added retry logic to the client.

Formerly, if there was an error in the client's connection
to the server, it would just quietly bomb out and fail to continue
initializing its state.  Now it will retry every 5 seconds.  Note
that if getChannelId fails it will still just not function correctly.
Manga Cam
Fixes
Add WebGL feature requirements
Creepy screen when getUserMedia failed
Readme links to only one sample - the old one.
Readme links to only one sample - the old one.
add directory access to filesystem sample

Update the fileSystem sample to show how to use the new directory
access feature in Chrome 31.
Merge pull request #137 from joemarini/master

add directory access to filesystem sample
added screenshot thumbnails and a new generic README.md
Merge branch 'master' of github.com:GoogleChrome/chrome-app-samples
added small version of CWS tryitnow button
fixed wrong sized try it now image
bumped versions to force republish
fixed CWS id of keyboard-handler and window-state samples
Merge pull request #128 from mrdewitt/push-guestbook-retry

push-guestbook: Added retry logic to the client.
Use notifications instead of polling in the Windows sample app
added screenshot for gdrive sample
Merge branch 'master' of github.com:GoogleChrome/chrome-app-samples
bumped version to publish