Jsoneditor

- Implemented history: undo/redo all actions.
- Created menu icons (instead of text buttons).
- Cleaned up the code (removed unused params, improved comments, etc).
- Minor performance improvements.

- Changed: description of advertisement now gives information about the Chrome
App (without ads).
- Changed: Chrome App is now configured to be available offline.
- Fixed: When zooming your browser window, the fields/values did get wrapped
on Chrome (thanks Henri Gourvest), and on Firefox sometimes the jsoneditor
disappeared due to wrapping of the interface contents.

- Changed: changed code for the buttons to copy from formatter to editor and
vice versa, no inline javascript (gives security policy errors in chrome app).

- Changed: other bootstrapping mechanism for the chrome app, in a separate
javascript file, as inline javascript is not allowed (security policy).
- Fixed: drop down menu for changing the field type did throw javascript errors
(did not break any functionality though).

- New: Chrome app created.

- New: Improved icon, logo, and interface header.