compute test fix

Change-Id: Ie431e9871a7da78b5a3924bfbc51d5575d994d86
Add session.py from OpenStackSDK

Added from commit b065d05c

Change-Id: I0ec4faca9bafbe94f9c9fe2528d1ed1985a3419f
Changes required for session.py from openstacksdk

Update import paths and module names

Change-Id: Idd5658dfe3862c0a74ea21f56ed8682fd5d97690
Switch restapi to use new session.Session()

Change-Id: I0ebdfa77b53cf89a6adc3fc68cf056f2cbc93112
Merge branch 'new-session' into dt-test
Merge branch 'compute-test-fix' into dt-test