Context page reorganization

- c716728 - Provide some more information to users about how to register their delivery details.
- 1df6c04 - Allow the user to delete pending confirmations.  So that they can start over.  Fixes fedora-infra/fmn#20
- 0c8c9ad - Furthermore, hide panels if context is yet unable to send.
- 8c4d64b - Hide panels if context is not active.
- 6c7265e - Move the new-filter form on the context page over to the left.