Implemented Repository Sets in CLI

Added test for subscribtions.

Requires manifest containing specific repository to work, in this case:
'Red Hat Enterprise Virtualization Agents for RHEL 6 Workstation RPMs x86_64 6Workstation'

Works with this manifest:

http://pastebin.test.redhat.com/231686

Well, this is the way gkhachik implemented it long ago :)