Backport: Bootstrap no longer cleans up if it can't tell whether an environment is bootstrapped or not.

Conflicts:
	cmd/juju/bootstrap.go
	cmd/juju/synctools.go
Merge pull request #350 from katco-/v1.20-backport

Backport: Bootstrap no longer cleans up if it can't tell whether an environment is bootstrapped or not.

https://bugs.launchpad.net/juju-core/+bug/1340893

Conflicts:
	cmd/juju/bootstrap.go
	cmd/juju/synctools.go