Enable DeprecationWarning in test environments
Enable DeprecationWarning in test environments

Many deprecations are triggered early (on imports, for example)
before the warnings are enabled by the WarningsFixture in the
base test class.

To make sure all DeprecationWarning messages are emitted we enable
them via the PYTHONWARNINGS environment variable.

Change-Id: If29fae24dff93b60f575ce38bc4d3fee8c5923a9

Gitweijie/first_project,noironetworks/networking-cisco,Gitweijie/first_project,openstack/networking-cisco,Tehsmash/networking-cisco,noironetworks/networking-cisco,openstack/networking-cisco,Tehsmash/networking-cisco