Rendition Syncing and other bug fixes

Rendition Syncing:
The plugin now keeps track of article renditions both in the cloud and
locally. You can now sync the content of one rendition to the others.
The plugin will also keep track of which articles have been updated
sync the article has been pushed to the cloud so you can easily see
which articles need updated.
- Added dpsfa-sync class for syncing article renditions
- Articles and folios keep track of changes in content and metadata
- Article and folio views now show if an article is out of sync with
other renditions or the cloud

Bug fixes:
- fixed a bug in boostrap.php where DPSFA_URL was declared twice
- updated icons for the plugin in WP 3.8
- fixed sidecar importer to update the parent rendition on import
- added minor bug fixes for syncing folios from the cloud and
duplicating articles from a folio rendition
- took out hard coded list of devices and device list for folios pull
through the list in the settings page
- minor ui style changes