[RHEL] Manual support of backend RHEL intergation.

Modify makefiles:
    * to create local mirror of RHEL repo;
    * to include RHEL repo to ISO.
Add support of RHEL packages download to master node via puppet.
Add RHEL profile to cobbler.
Add minimal RHEL support to deployment procedure.
[nailgun] Add default user/pass values to fixture.
[nailgun] Fix unittest to use COBBLER_CENTOS_PROFILE.
added custom repotrack, more satellite code
Comments fixed.
fixed typos in rpmcache
[rhel] Move cobbler profile name to release attrs.
Remove subscr-mngr repo from mirror defines.
[nailgun] Fix tests.
[nailgun] Fix attributes_metadata in tests.