Add Env and SetEnv methods to command.Meta to retrieve the current
environment name inside any command.
Make sure all calls to Backend.State contain an environment name, and
make the package compile against the update backend package.
Remove the lock command for now to avoid confusion about the behavior of
locks. Rename lock to force-unlock to make it more aparent what it does.
Add a success message, and chose red because it can be a dangerous
operation.
Add confirmation akin to `destroy`, and a `-force` option for
automation and testing.
James Bardin