Dump error message when instance couldnt build

[mat128]

An error occurred while executing the action on the 'test.example.org'
    [exec] machine. Please handle this error then try again:
    [exec] 
    [exec] While creating the server, it transitioned to an unexpected
    [exec] state: 'ERROR', instead of properly booting. Run `vagrant status`
    [exec] to find out what can be done about this state, or `vagrant destroy`
    [exec] if you want to start over.