Support remote host

[sleekweasel]

Two commits here - one stealing a file from ddmlib, the other the actual changes.

I don't expect you to pull this, with the ddmlib file hauled in, but I don't know what branch to configure in my main Android source repo to suggest the ddmlib change - do you know?

I'm mostly putting this here to refer to my ADB_SERVER_SOCKETS issue - this uses the ANDROID_ADB_SERVER_PORT and ADBHOST environment variables, which are correlated.