docker-setup: ensure ubuntu user exists

The default configuration uses ssh keys in the ubuntu user's $HOME.
Check if this user exists and create it (and the .ssh directory) if not.
Merge pull request #485 from dgryski/docker-setup-create-ubuntu-user

docker-setup: ensure ubuntu user exists
router/elb: implemented add backend.
router/elb: refactored add backend tests.
router/elb: implemented remove backend.
router/elb: simplified add backend.
router/elb: added defer to remove backend.
router/elb: implemented add route.
router/elb: implemented remove router.
router/elb: implemented addr.
router/hipache: added more logs in add route.
router: fixed a typo.
Fix typo in error message
Merge pull request #487 from sidnei/master

Fix typo in error message.
added Sidnei da Silva in AUTHORS and CONTRIBUTORS.
Rename ProvisionUnits to ProvisionedUnits since it is a method that returns provisioned units, not a method to provision them.
Merge pull request #491 from sidnei/master

Rename ProvisionUnits to ProvisionedUnits since it is a method that returns provisioned units, not a method to provision them.
provision/juju: added a method to return the router.
router/elb: added support for vpc.
provision/juju: using router for add/remove elb.