Re-submit "ML2 plugin should not delete ports on subnet deletion"

This patch was previously merged:

Commit: 0d131ff0e9964cb6a65f64809270f9d597c2d5d1

And reverted by this commit da00ed76e6008bd06dada0f0441ae436dd759cdf
in order to check if there was a relation with the gate failures.

Change-Id: Iacb4de8d9aa6a6cbe32c4f41fcf2657f2d09e6e2
Fixed floating IP logic in PLUMgrid plugin

  * Fixed associate and disassociate
    floating IP logic
  * Added unit tests

Change-Id: I310f5550bca1c9015cbda3e0338eb90a36dc96f1
Closes-Bug: 1298495
LBaaS: remove orphan haproxy instances on agent start

This change adds remove_orphans() handling to the haproxy
namespace driver. remove_orphans() is already called by
lbaas agent on start for all drivers

Closes-Bug: #1262885
Change-Id: I5deae8e56c2cd2deb1667e9646633fd59a94b34e
Merge "Re-submit "ML2 plugin should not delete ports on subnet deletion""
Merge "Fixed floating IP logic in PLUMgrid plugin"
Merge "LBaaS: remove orphan haproxy instances on agent start"