schema: verification of API.py and schema during UT

In order to automate verification of API changes with schema we added
a unit test which breaks build if there is any discrapency.

The verification covers most of issues found:
- number of args in verb and schema
- optional args in schema vs default args in api
- return value in command_info and schema

Due to API module being loaded for schema verification we needed to
fix bridgeTests.py

Change-Id: If81cff3c988e00c8c4eda1809f481e1ae19398dd
Signed-off-by: pkliczewski <piotr.kliczewski@gmail.com>
Reviewed-on: http://gerrit.ovirt.org/35557
Reviewed-by: Francesco Romani <fromani@redhat.com>
Reviewed-by: Yaniv Bronhaim <ybronhei@redhat.com>
Reviewed-by: Dan Kenigsberg <danken@redhat.com>