amended the previously missed Bigip_Failover_State class to inherit from ResourceBase. Minor code change to rectify travis error

Author: wojtek0806

f5/bigip/resource.py

@@ -329,8 +329,8 @@ def _check_required_parameters(rqset, **kwargs):
         key_set = set(kwargs.keys())
         required_minus_received = rqset - key_set
         if required_minus_received != set():
-            error_message = 'Missing required params: {}'\
-                .format(required_minus_received)
+            error_message = 'Missing required params: %s' % \
+                            required_minus_received
             return True, error_message
         else:
             return False

f5/bigip/tm/shared/bigip_failover_state.py

@@ -27,10 +27,10 @@
 """
 
 from f5.bigip.mixins import UnnamedResourceMixin
-from f5.bigip.resource import Resource
+from f5.bigip.resource import ResourceBase
 
 
-class Bigip_Failover_State(UnnamedResourceMixin, Resource):
+class Bigip_Failover_State(UnnamedResourceMixin, ResourceBase):
     """BIG-IP® failover state information
 
     Failover state objects only support the