Added Support for Thumbnail Generation

Code Review Progress: http://mrccodereview.cloudapp.net/ui#review:id=1152

Added support for thumbnail generation when a content items gets saved. To support this scenario correctly, added:
- Added http://server/chronozoom.svc/info endpoint to retrieve the thumbnails path. This endpoint can be extended with additional server information as needed.
- Added web.config setting to configure connection to thumbnail storage
- Added web.config setting to point to the thumbnails server.

Misc: Fixed SeaDragon broken icons while browsing within a collection.