add ec2 tests

Change-Id: Iced3eb8ca81c3b067496c3683f322b6e1dedec2a
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
Update release notes for 0.next

Change-Id: Iad6cfe5dee63adb9e60a0ea9811217b3175eb99c
Merge branch 'review/qiu_yu/refactor-role-list-cmd' into dt-test
Merge branch 'hacking-hack' into dt-test
Merge branch 'timings' into dt-test
Merge branch 'fix-logging' into dt-test
Merge branch 'release-0.next' into dt-test
Merge branch 'new-session' into dt-test
Merge branch 'identity-ec2-tests' into dt-test