blueprint devstack-support-for-keystone-mixbackend

Added KEYSTONE_ASSIGNMENT_BACKEND to support mixed backend

Modified code for KEYSTONE_IDENTITY_BACKEND according to comments.
Implemented the check for variables instead of case statements.
UPD: Removed arrays.
UPD2: fixed spacing issues
Change-Id: Ie92eed1fb5be5f875ef6633ede9c9e08daf6bf4f
Implements: devstack-support-for-keystone-mixbackend
Disable ceilometer.compute.nova_notifier driver

It appears that the ceilometer nova notification driver is causing
nova-compute to hang.  The last thing nova-compute logs before hanging
is a line from this driver.  At the very least the ceilometer nova
notification keeps stacktracing.

Change-Id: Ic375272b751159a64777ca73c1b64515195aacfb
Related-Bug: #1221987
lib/tempest remove whitebox section

tempest whitebox tests are removed from the tempest repo, so it's
configuration is unnecessary.

Change-Id: I6659e2af894014518a486f411ca06179d43bbb8b
Merge "blueprint devstack-support-for-keystone-mixbackend"
Merge "Disable ceilometer.compute.nova_notifier driver"
Merge "lib/tempest remove whitebox section"
Merge branch 'master' of github.com:openstack-dev/devstack