Changes

templates: osmo-msc: modernize

Configure the mgw in the mgw node, and drop the obsolete commands
endpoint-range and bts-base.

Fix for:
| Error occurred during reading the below line:
|  mgw bts-base 8000
|
| % MGCP commands outside of 'mgw' nodes are deprecated. You should consider reading User Manual and migrating to 'mgw' node.

Change-Id: I077c4cd4c593da776a306117ad2a898a82d91064