Migrate negative test to a different file

Here added a different file to store
negative tests of migration.

Partially implements blueprint negative-test-files

Change-Id: I1791265882d0fd748445c39884906983068b5179
Minor changes to scenario manager

Use native neutron client to retrieve tenant's resources instead of filtering
in tempest

Change variable name

I have a few patches that require this added functionality

Change-Id: I7b3685c8f002b460dae0c9fd4b8602b19cf914a7
Adds cinder backup functional tests

Adds new tests to cover cinder backup api as well as the needed
json clients.

xml client will be submitted after bug #1270589 is fixed.

Change-Id: I8d40c58eaf0ccd24abf55a212f1177e61ef0a281
Closes-Bug: 1221335
Merge "Adds cinder backup functional tests"
Merge "Minor changes to scenario manager"
Merge "Migrate negative test to a different file"
Merge branch 'master' of https://github.com/openstack/tempest