Adding l3_ext network type for NSX support

blueprint: ml2-neutron
related-blueprint merge-openstack-puppet-modules

Upstream vsphere patch id: Ibabe05ebfa6315285c72465da2eadc989b3a9312
Change-Id: Ia2fbd151e5f5b7e31f090974f9a2ee58e4a087cc
Merge "Adding l3_ext network type for NSX support"