Added support for NOS version 4.1.0, 5.0.0 and greater

NETCONF temaplates for NOS version greater than 4.1.0 are slightly
different (argh). An init time check of the NOS version is done
to enable selection of the correct NETCONF templates.

Change-Id: I01e82ad402fbbb25d92a99a3325ca2608dd514cb
Closes-bug: #1332719
ofagent: Handle device name prefixes other than "tap"

This fixes regressions in commit 9d13ea884bff749b3975acb5eb5630e5aca4a665.

Handle device name prefixes other than "tap".
For example, nova hybrid interface driver uses "qvo" prefix.

Also, ignore non neutron ports correctly.  For example, veth pairs
used to connect physical bridges.

Closes-Bug: #1341465
Change-Id: I1d71c8a2cf8c2f71f0dbcfb54c9b347e24c03562
Fixes port update failure when device ID is not updated

The updation was failing because the changed_device_id variable
was undeclared.This fix declares the variable with a default value
at the beginning of the method.

Change-Id: I06dfea1170a6b2a649f4e1efe4bf70b7cee0eacb
Closes-Bug: 1337787
Big Switch: Remove consistency hash on full sync

Clears the consistency hash before performing a full
backend synchronization. Since all of the data is being
replaced, there is no reason to include this and it
currently requires special-casing to handle.

Closes-Bug: #1328233
Change-Id: Iace766d869dc78b041d3a5464e728b872c8347c2
Merge "Fixes port update failure when device ID is not updated"
Merge "Added support for NOS version 4.1.0, 5.0.0 and greater"
Merge "Big Switch: Remove consistency hash on full sync"
Merge "ofagent: Handle device name prefixes other than "tap""