Wire up placement directives to EnsureAvailability api
Fix facade version detection
Code revew fixes
Rework how support for legacy installs is handled
Fix client fallback
Fix typos
Fix tests
Merge branch 'master' into ensure-availability-to-2
Fix test
Merge pull request #771 from wallyworld/ensure-availability-to-2

Wire up placement directives to EnsureAvailability api

When "juju ensure-availability --to machine1, machine2" is run, the placement directives are added to the machine template and so are used when the new instance is created. This is similar to how bootstrap works.

The API added by the previous branch needed to be tweaked to hook things up.

Fixes: https://bugs.launchpad.net/juju-core/+bug/1370332

http://reviews.vapour.ws/r/38/