[VOL-2241] Python 3 refactor of pyvoltha

Majority of work was manual fixes to bytes and strings types, which are
different in py3, but same in py2. As the OMCI library does a lot of
these comparisons and scapy then renders packets, this was frequently
nontrival to debug.

Also:

- Removed grpc dep which wasn't being used, not py3 compatible
- s/Alarms/Events/ to work with protobuf changes per VOL-2224
- Automatic fixes via modernize tooling
- Removed unused OrderedWeakValueDict code
- Removed frameio send_frame specific to Darwin (MacOS), which had no
  corresponding linux code
- Use library functions for hex and unicode conversions
- Various other cleanups and fixes (EOL whitespace, etc.)

Also more (Matt):

 - handle stringify better, check if already string
 - use binary string for binary work
 - import new thread paths
 - update requirements.txt for newer libraries needed with newer python
 - return proper tuple for unpacking
 - bytes string formatting fixed
 - fix mock task unit test

Even more (Zack):

- Python 2/3 compat for _thread by using 'future'
- Bump version to 2.3.0

Change-Id: I53b596d374a944bfb80d0b112f21bcc1f8bcee6e
diff --git a/test/unit/extensions/omci/test_mib_resync_task.py b/test/unit/extensions/omci/test_mib_resync_task.py
index 892cd97..7294309 100644
--- a/test/unit/extensions/omci/test_mib_resync_task.py
+++ b/test/unit/extensions/omci/test_mib_resync_task.py
@@ -13,12 +13,13 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 #
+from __future__ import absolute_import
 from unittest import main, TestCase
 from pyvoltha.adapters.extensions.omci.omci_entities import *
 from pyvoltha.adapters.extensions.omci.tasks.mib_resync_task import MibResyncTask
 from pyvoltha.adapters.extensions.omci.database.mib_db_dict import MibDbVolatileDict as OnuDB
 from pyvoltha.adapters.extensions.omci.database.mib_db_ext import MibDbExternal as OltDB
-from mock.mock_adapter_agent import MockAdapterAgent, MockDevice
+from .mock.mock_adapter_agent import MockAdapterAgent, MockDevice
 
 _DEVICE_ID = 'br-549'
 
@@ -145,7 +146,7 @@
         class_id = OntG.class_id
         inst_id = 0
         attributes = {
-            'extended_tc_layer_options': long(0x1234),        # BitField(16)
+            'extended_tc_layer_options': int(0x1234),        # BitField(16)
         }
         self.onu_db.set(_DEVICE_ID, class_id, inst_id, attributes)
         self.olt_db.set(_DEVICE_ID, class_id, inst_id, attributes)