remove osc from project explicit dependencies

OSC is not really required to use otcextensions. It provides, however, 
plugin to OSC which will be used if required

Author: gtema

requirements.txt

@@ -2,6 +2,5 @@
 # of appearance. Changing the order has an impact on the overall integration
 # process, which may cause wedges in the gate later.
 
-python-openstackclient>=3.14.0 # Apache-2.0
 openstacksdk>=0.16.0 # Apache-2.0
 boto3>=1.4.6 # ASL-2.0

test-requirements.txt

@@ -14,7 +14,7 @@ stestr>=1.0.0 # Apache-2.0
 testrepository>=0.0.18 # Apache-2.0/BSD
 testscenarios>=0.4 # Apache-2.0/BSD
 testtools>=2.2.0 # MIT
-python-openstackclient!=3.12.0 # Apache-2.0
+python-openstackclient>=3.12.1 # Apache-2.0
 tempest>=17.1.0 # Apache-2.0
 
 boto3>=1.4.6 # ASL-2.0