port to gofer 2.1.

Updated to work with gofer 2.1.  Latest upstream and in Fedora 21.
- improved support for multiple messaging adapters (formerly transports).
- standardized url which includes messaging adapter.  format: *adapter*+*scheme*://*user*:*password*@*host*:*port*/*virtual-host*  instead of the *transport* option.
- hundreds of new unit tests.
No longer needed since the pulpplugin is loaded from python path.  Matches the pulp.spec.