introduce if/then & for/do rules

we mostly have a consistent style on if/then & for/do in devstack,
except when we don't. This attempts to build a set of rules to
enforce this.

Because there are times when lines are legitimately long, and there
is a continuation, this starts off ignoring if and for loops with
continuations. But for short versions, we should enforce this.

Changes to make devstack pass are included. The fact that the
cleanup patch was so small is pretty solid reason that this is
actually the style we've all agreed to.

Part of a git stash from hong kong that I finally cleaned up.

Change-Id: I6376d7afd59cc5ebba9ed69e5ee784a3d5934a10
Merge "introduce if/then & for/do rules"
Merge branch 'master' of github.com:openstack-dev/devstack