Remove provider from status (Vagrant 1.1)

Current status includes the provider in the following format: 

```
Current machine states:

testbox10                running (virtualbox)
testbox20                not created (virtualbox)
```

This PR strip the provider name out of the status and would return the following: 

```
>>> import vagrant ; v = vagrant.Vagrant() ; v.status()
{'testbox20': 'not created', 'testbox10': 'running'}
```