Bootstrap Endpoint Address

After Bootstrap returns successfully, get the bootstrap instance and
write its addresses to jenv/environ info/connection info.
Merge branch 'master' of https://github.com/juju/juju into endpoint-on-bootstrap-take3

Conflicts:
	cmd/envcmd/environmentcommand.go
	cmd/juju/bootstrap_test.go
Merge branch 'master' into endpoint-on-bootstrap-take3
Fix merge conflicts
Merge pull request #519 from waigani/endpoint-on-bootstrap-take3

Bootstrap Endpoint Address

After Bootstrap returns successfully, get the bootstrap instance and
write its addresses to jenv/environ info/connection info (choose
your name).