add support to get VM status when calling for a single instance

concurrent request
Ref TheWeatherCompany/grid-api#509
removed concurrency for vm status in getVM call

also incorporate new VirtualMachineStatus object
Ref TheWeatherCompany/grid-api#509
allow for null value to be passed into getVMStatus

Will return all vms if null
Ref TheWeatherCompany/grid-api#509
Merge pull request #61 from TheWeatherCompany/support-to-get-vm-status

Support to get vm status