Create LinuxAdmin::RegistrationSystem
Modify Inheritence
Fix tests related to registration_system commands
Change Rhn class methods to instance methods
Change SubscriptionManager class methods to instance methods
Move subclasses into a folder
Merge pull request #33 from brandondunne/modify_rhn_and_subscription_manager_to_inherit_from_registration_system

Modify rhn and subscription manager to inherit from new registration system class