OS-240, OS-242: patch threading and drop vms-2.6

In Havana, nova's code uses threading, thus requiring it to be
monkeypatched.  Unfortunately, some of vms's python code doesn't work
if threading is monkeypatched. In particular, blessing doesn't work
with monkeypatched threading since it creates threads. Fortunately,
starting with vms-2.7, we use vmsctl to bless, so we can monkeypatch
threading and make nova happy.

To deal with this problem, we've decided to drop vms-2.6 support
entirely and monkeypatch threading. We could have limited this patch
to Havana+, but, in the interest of keeping cobalt versions in sync
with respect to vms compatibility, we've decided to drop vms-2.6
support across the board for cobalt 1.4.

This patch is minimal with repsect to dropping vms-2.6. In upstream
branches (1.5), we remove all of the vms-2.6 related code.

Change-Id: I995231997d513199edb2c97a97ca66508cc2d4c5
Merge 'OS-240, OS-242: patch threading and drop vms-2.6' from grizzly/1.4

Since vms-2.6 support has already been dropped in grizzly/1.5, the
effect of this merge is to just fix OS-242 by patching threading.

Conflicts:
    cobalt/nova/extension/vmsapi.py

Change-Id: I97a513a29914bfd523f5885686a442360deedcba
Merge 'OS-240, OS-242: patch threading and drop vms-2.6' from grizzly/1.4

Change-Id: I932a6d19777fdae56cc97758dce458f6bfca2deb
Merge 'OS-240, OS-242: patch threading and drop vms-2.6' from havana/1.4

Since vms-2.6 support has already been dropped in havana/1.5, the
effect of this merge is to just fix OS-242 by patching threading.

Conflicts:
	cobalt/nova/extension/vmsapi.py
	cobalt/tests/test_vmsapi.py

Change-Id: Icec9aeb2b40b8f18ee596fcb1ced1d39b211ca76
Merge 'OS-240, OS-242: patch threading and drop vms-2.6' from grizzly/1.5

Simply syncing havana/1.5 with grizzly/1.5. No changes introduced.

Change-Id: I25b0ed2f6f9d57ea57a02730bf7f678404bdb43b