Adding weight column to Neutron lb member list CLI

Adding 'weight' column to lbaas member-list command in order to quickly
identify member properties. Protocol port was already been shown.
This avoids having to enter each member details to see the weights
settings.

Change-Id: Id3c8cd8b3304535e2d82777018121007ed3bb129
Closes-Bug: #1267575
Merge "Adding weight column to Neutron lb member list CLI"