Added missing MessageNotRunning action

I ran `vagrant provision` within a halted machine and throw this exception

```
$ vagrant provision  --provision-with=puppet
/home/esteban/.vagrant.d/gems/gems/vagrant-kvm-0.1.4/lib/vagrant-kvm/action.rb:137:in `block (3 levels) in action_provision': uninitialized constant VagrantPlugins::ProviderKvm::Action::MessageNotRunning (NameError)
	from /opt/vagrant/embedded/gems/gems/vagrant-1.2.7/lib/vagrant/action/builtin/call.rb:47:in `call'
	......
        (useless backtrace here)
	......
```

Fixed it and now it shows a user friendly message :grimacing:

```
$ vagrant provision
[default] VM is not currently running. Please, first bring it up with `vagrant up` then run this command.
```