Code review comment for lp:~axwalk/juju-core/synchronous-bootstrap

Reviewers: mp+196058_code.launchpad.net,

Message:
Please take a look.

Description:
Implement synchronous bootstrap

environs/manual has been further refactored to
split the "manual cloud-init over SSH" out into
a separate package (cloudinit/sshinit).

provider/common now starts an instance with the
basic cloud-init only (SSH keys + logging), then
waits for a DNS name, waits to be able to connect
via SSH, and then defers to sshinit to execute the
remaining cloud-init steps.

If the user hits Ctrl-C, SIGINT will terminate
the SSH connection, and the bootstrap process will
attempt to clean up by stopping the instance and
removing the state file (if the instance could be
cleanly stopped). We also ignore SIGINT in the
juju process so a second Ctrl-C will not terminate
the cleanup procedure.

Fixes #1224230

https://code.launchpad.net/~axwalk/juju-core/synchronous-bootstrap/+merge/196058

(do not edit description out of merge proposal)

Please review this at https://codereview.appspot.com/30190043/

Affected files (+334, -88 lines):
   A [revision details]
   M cloudinit/options.go
   M cloudinit/sshinit/configure.go
   M cloudinit/sshinit/configure_test.go
   A cloudinit/sshinit/suite_test.go
   M cmd/juju/bootstrap.go
   M environs/bootstrap/state.go
   M environs/bootstrap/state_test.go
   M environs/cloudinit.go
   M environs/cloudinit/cloudinit.go
   M environs/cloudinit_test.go
   M environs/manual/bootstrap.go
   M environs/manual/detection.go
   M environs/manual/provisioner.go
   M provider/common/bootstrap.go
   M provider/common/bootstrap_test.go
   M provider/ec2/local_test.go
   M provider/maas/maas_test.go
   M provider/openstack/local_test.go
   M utils/ssh/ssh.go