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
(cherry picked from commit f807023246501b77e792371d98b612b208f5e8e3)
Merge "Added support for NOS version 4.1.0, 5.0.0 and greater" into stable/icehouse