tests/unit/ryu/test_ryu_db: db failure

tests/unit/ryu/test_ryu_db: db failure

Fixes bug 1061408

The unit test of test_ryu_db fails when it is specified to run as follows.

$ ./run_tests.sh quantum.tests.unit.ryu.test_ryu_db
RyuDBTest
    test_ofp_server (quantum.tests.unit.ryu.test_ryu_db.RyuDBTest)ERROR

======================================================================
ERROR: test_ofp_server (quantum.tests.unit.ryu.test_ryu_db.RyuDBTest)
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Traceback (most recent call last):
  File "/quantum/tests/unit/ryu/test_ryu_db.py", line 30, in setUp
    options = {"sql_connection": cfg.CONF.DATABASE.sql_connection}
  File "/quantum/openstack/common/cfg.py", line 1039, in __getattr__
    return self._get(name)
  File "/quantum/openstack/common/cfg.py", line 1361, in _get
    value = self._substitute(self._do_get(name, group))
  File "/quantum/openstack/common/cfg.py", line 1377, in _do_get
    info = self._get_opt_info(name, group)
  File "/quantum/openstack/common/cfg.py", line 1470, in _get_opt_info
    raise NoSuchOptError(opt_name, group)
NoSuchOptError: no such option: DATABASE

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Ran 1 test in 0.001s

Change-Id: Ie639914c64e6fba10112a58efa7f363615d0c9fd