google: Don't log failure to connect to ERROR.
google: Don't log failure to connect to ERROR.

Currently, if the GCE client fails to connect, it logs an ERROR-
level log message, which is misleading if the user wasn't trying
to launch anything on GCE. This commit changes the behavior to
be consistent with the other clusters: the error gets returned
to the cluster launch code, which then logs it at DEBUG level.

ejj/quilt-dev,kklin/quilt,quilt/quilt,LuiseV/quilt,NetSys/quilt,kayousterhout/quilt,quilt/quilt,kklin/kelda,kklin/kelda,LuiseV/quilt,NetSys/quilt,kklin/quilt,kklin/kelda,tejasmanohar/quilt,kelda/kelda,kklin/kelda,ejj/quilt-dev,kelda/kelda,LuiseV/quilt,kelda/kelda,tejasmanohar/quilt,kayousterhout/quilt,kayousterhout/quilt,quilt/quilt,tejasmanohar/quilt,NetSys/quilt,LuiseV/quilt,ejj/quilt-dev,kayousterhout/quilt,quilt/quilt,LuiseV/quilt,kelda/kelda,kklin/quilt,tejasmanohar/quilt,NetSys/quilt,NetSys/quilt,kklin/quilt,ejj/quilt-dev