Adding support for admin_state_up flag

This commit enhances the port, bridge and router resources with
the admin_state_up flag.

Change-Id: Ib2231b040026e7918d90b40a36afd80af0048603
Added missing newline

Change-Id: Ib241c0c354de84479669f1a60eda8b0c1c49a2c8
Merge pull request #79 from duarten/master

Adding support for admin_state_up flag