Accept Non-Tor Platform line in Server Descriptor
Stem currently assumes the platform line in the server descriptor starts with "platform Tor".
platform_match = re.match("^Tor (\S*).* on (.*)$", value)
There exist other implementations which say something else, such as "platform node-Tor". Maybe changing "
^Tor" to "(\w*)" will work, but there could be a better way.