Retry and delete buttons for failed items

* Removes the "retry upload on click" from contribs list
* Replaces the detail view's toolbar buttons with "retry" and "abort" buttons for failed uploads
* 'retry' retries, and delete deletes. both kick you back up to the list as well.
* implemented 'delete' on contribs content provider

I'm not 100% happy with the placement of the methods, but can move em later.