Merge pull request #634 from wallyworld/keep-env-flag

Add bootstrap flag to allow failed bootstraps to keep the environment

Fixes: https://bugs.launchpad.net/juju-core/+bug/1362923

bootstrap now has a keep-broken flag which tells it not to cleanup after a failed bootstrap
Fix test
Merge pull request #635 from wallyworld/keep-env-flag-1.20

Merge pull request #634 from wallyworld/keep-env-flag

Add bootstrap flag to allow failed bootstraps to keep the environment

Fixes: https://bugs.launchpad.net/juju-core/+bug/1362923

bootstrap now has a keep-broken flag which tells it not to cleanup after a failed bootstrap