Make sure we don't wait for the AC forever.

Right now we'll wait for at most 15 minutes. Possibly a bit too long of a
timeout.
Let's make sure we terminate failed instances.

If the AC is not responsive, we should make sure we terminate the
instance.
On failure, terminate the whole infrastructure.
Addressed comments in pull request.
Merge branch 'master' into AC_wait_timeout
Merge pull request #388 from obino/AC_wait_timeout

Ac wait timeout