el6 is shipped with Python 2.6.x which is not expected
to be supported with the openstack kilo release.
For el6 support we need to do lot of thing differently,
which makes the code more complicated.
This change removes el6 and py26 support from devstack.
This change also removed a discontinued (1 year ago)
openSUSE 12.2 code path, which used a similar codepath as el6.
Several comment related to el6 also removed or modified.
Change-Id: Iea0b0c98a5e11fd85bb5e93c099f740fe05d2f3a
1f316beb20