Merge pull request #55 from brandondunne/Add_use_case_to_yum_spec_version_available

Add use case to yum spec version available
further parameterize disk#create_partition, accept params for % of free space
Merge pull request #52 from movitto/create_partitions_percentages

further parameterize disk#create_partition, accept params for % of free ...
Add #subscribed_products method and auto-attach to #subscribe
Change pools to channels to be different from SubscriptionManager
Add #subscribed_products to Rhn
Update tests