Added functionality to set baud rate of the serial port on initialization: /dev/ttyACM0@115200 will init the port with a baud rate of 115200.
Backward compability is given, as if no baud rate is specified, like /dev/ttyACM0 the serial binding defaults to 9600 bauds.
Merge pull request #1897 from wishmoooop/master

[Serial] Baud rate selection on serial binding as parameter