one_session branch working with win7

This is now working on windows 7 and follows the approach we discussed of counting operations. I ended up taking the code in the latest WinRM dev branch that has my latest file copy code and copying it over because its cleaner and organized in such a way that tracking state on the shell is easier.

Unfortunately the lookup commands on the maxConcurrentOperationsPerUser property are also blocked remotely so I base the limit on your OS version. There is a slim chance that a user may have tweaked these but likely to increase them so I think this is pretty safe.

There was also a small but significant powershell snippet that broke in psv2 so had to fix that too and will be porting both fixes to winrm. Really glad you caught this! When winrm v1.3 releases, we can delete most of this code (yay!).

I'm gonna look into the busser copying next. Let me know if you run into any issues here.