Fixes lp:1339976, lp:1270466

lp:1270466
Add the following cmd to add-machine:

juju add-machine ssh:user@10.10.0.3 -i ~/myid.pub

where -i is a specific identity key used to ssh into the machine. The key is also stored in the machine for future logins.

lp:1339976
This PR also fixes a bug where cloudinit was not using the ssh client.
Merge branch 'master' of https://github.com/juju/juju into manual-prov-key

Conflicts:
	cmd/juju/addmachine.go
	cmd/juju/addmachine_test.go
Merge branch 'master' of https://github.com/juju/juju into manual-prov-key
Merge branch 'master' of https://github.com/juju/juju into manual-prov-key
Merge branch 'master' of https://github.com/juju/juju into manual-prov-key
Merge branch 'master' of github.com:waigani/juju into manual-prov-key
Updated version of golxc.
Merge branch 'master' of github.com:katco-/juju
Merge branch 'master' of https://github.com/juju/juju
Don't expose state port for openstack provider
state/apiserver/usermanager: fix potential panic
state/apiserver: derive svrRoot authorier from state.Entity
Do not open state port. ec2 and azure.
Do not open state port. ec2 and azure.
Remove last mention of StatePort in azure provider tests
Merge branch 'master' into manual-prov-key
Partial fix for LP-1351089
Fixed incorrect mgo import
Merge pull request #451 from mjs/fix-mgo-import

Fixed incorrect mgo import
LP-1351089 :: Isolate tests from users BASH_ENV