Warn if a URI segment contains characters that conflict with Windows folder naming

[jautor]

Related to this issue: DMTF/Redfish-Mockup-Creator#72

Suggest we add a warning (not a failure) if the validator finds a URI segment that contains characters that conflict with Windows folder naming rules. While those don't violate the Specification, they will cause problems for any use cases that involve saving payloads on a Windows-based system.

[mraineri]

I need to think about this one a bit; it seems odd to me to flag a valid service just because of a Windows limitation, but I can understand concerns if a Windows-based client is going to be making directories off of the Id properties in resources.