Fetch routers ports for metadata access from DB

Bug 1176963

There is no need to retrieve the ports from the NVP backend, so
a DB query will be enough.

Change-Id: If3529cc5694434e8cdc9d21a4043f94212146d2d
(cherry picked from commit 0fee496538a36e7db5b7e2c7e5bbd5cff2aedd53)
Don't run metadata proxy when it is not needed

Bug #1159015

Change-Id: I6063e75525a2a727d063bb1745c897ac8c4ba3e8
(cherry picked from commit a397df38c748d482ece18e164084a589d7f2d362)
Merge "Fetch routers ports for metadata access from DB" into stable/grizzly
Merge "Don't run metadata proxy when it is not needed" into stable/grizzly