Make Swift uses API_WORKERS

Keep the default to 1 instead of going wild, cause Swift really would
kill the VM if we let it go (and keeps the old behavior).

Change-Id: I7449c1bb485459169b8870c871b887cbab8be865
Add trove-api to $API_WORKERS

Ie4bb075310a61a0873c9e56e4974600dbb4794a1 missed trove when adding
support for $API_WORKERS.

Change-Id: Iaeb43ef63596a61ad9c128e57d6a2d68b688719e
Merge "Add trove-api to $API_WORKERS"
Merge "Make Swift uses API_WORKERS"
Merge branch 'master' of https://github.com/openstack-dev/devstack