renamed backends to downloaders as there is no need for a backend without a proverbial frontend
got rid of download factory
removed protocol as a required keyword argument to the downloader config
Unit tests for remove commands
Merge pull request #160 from pulp/jdob-remove-command

Unit tests for remove commands
Merge pull request #150 from pulp/jconnor-other-downloader-implementations

Jconnor other downloader implementations
fixing some unit tests due to backends->downloaders rename
Merge branch 'master' into mhrivnak-newimporter
can now sync DRPMs