remove eventlet and monkey patch

Using eventlet for rpc enforces using eventlet.monkey_patch caused all
vitrage to affectivly use a single thread.
With this change, vitrage may use actual threads (mostly affects the main processor process).
This change passed thorough testing.

Change-Id: I71991d6f795e5c503c7226523e36c4fb7ab3835c

vitrage/api_handler/service.py

@@ -12,7 +12,6 @@
 # License for the specific language governing permissions and limitations
 # under the License.
 
-import eventlet
 from oslo_log import log
 import oslo_messaging
 from oslo_service import service as os_service
@@ -28,8 +27,6 @@ from vitrage import rpc as vitrage_rpc
 
 LOG = log.getLogger(__name__)
 
-eventlet.monkey_patch()
-
 
 class VitrageApiHandlerService(os_service.Service):
 

vitrage/rpc.py

@@ -96,6 +96,6 @@ def get_server(target, endpoints, transport, serializer=None):
     return messaging.get_rpc_server(transport,
                                     target,
                                     endpoints,
-                                    executor='eventlet',
+                                    executor='threading',
                                     serializer=serializer,
                                     access_policy=access_policy)