Nuage plugin was missed in floatingip_status db migration script

The fix for bug 1287630 did not include the the Nuage plugin
in those affected by the migration.
Nuage CI started failing floatingip tests since than
reporting unknown column error.
This bug fix is to add nuage plugin to the list.

Change-Id: I7133fc97d65618549f72d7649232002cbb640bbb
Closes-bug: 1288929