SerialPort Flow Control

@ taylorza probably worth bugging your serial port find over on codeplex (edited for clarity)

@ Brett - I will definitely do that. I just want to write a test to confirm that I did not misinterpret that code, I was not really focusing on it at the time it just caught my eye while I was navigating towards the core .NETMF code for the serial port.

I will make a point of getting it done tonight!