Fix pool update error in lbaas

fixes bug 1185687

Do not notify namespace agent of modified pool
if pool doesn't have vip

Change-Id: Ibe3399aaa145d19fc758f08adb51c7ffefa5bb3a
Fix Cisco nexus plugin failure for first VLAN on phy interface

Fixes bug 1174852

This fix changes the command being sent to the Nexus switch for
enabling a VLAN on an interface such that the 'add' keyword is
included only when there are prior VLANs already enabled on that
interface.

Change-Id: I466bcb839912b164b84be0e6721d87206c0e53eb
Merge "Fix pool update error in lbaas"
Merge "Fix Cisco nexus plugin failure for first VLAN on phy interface"