Jortel 1115631

https://bugzilla.redhat.com/show_bug.cgi?id=1115631
```
[jortel@localhost sources]$ nosetests --with-coverage --cover-package=pulp.server.content.sources 
................................................................
Name                                     Stmts   Miss  Cover   Missing
----------------------------------------------------------------------
pulp.server.content.sources                  2      0   100%   
pulp.server.content.sources.constants       25      0   100%   
pulp.server.content.sources.container      114      0   100%   
pulp.server.content.sources.descriptor      36      0   100%   
pulp.server.content.sources.model          176      0   100%   
----------------------------------------------------------------------
TOTAL                                      353      0   100%   
----------------------------------------------------------------------
Ran 64 tests in 0.046s
```