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: Ie91cdc1920fd39c1f4dc6ffd101c70ca2b794758

openstack/networking-nec,stackforge/networking-nec,stackforge/networking-nec,openstack/networking-nec