SCVMM linux VMs have error message in their hostname

Linux VMs that do not have the Integration Services installed cannot communicate guest information back to the Hyper-v server. The 'hostname' is one example of this, instead of displaying a blank value or a descriptive warning for the hostname, powershell displays the following ugly error:
 "getaddrinfo failed_x000A_ "
This PR addresses this by gracefully replacing this error message with the string "Unavailable" as the hostname property value. I am open to enhancing this to "Integration Services not installed" or something along those lines.

https://bugzilla.redhat.com/show_bug.cgi?id=1138774
Good question.  The it's tough to know what to put here... I kinda wanna direct the user to the logs.  But, that seems like overkill for the hostname.

I think "unavailable" is fine as long as we also doc that this means the user should check the logs.