Update mavlink_serial.cpp

corrected configuration for baudrate higher than 115200
tested in Ubuntu14.04
Update mavlink_serial.cpp
Update send_quad_commands.cpp
Merge pull request #2 from ziyangli/patch-1

Update mavlink_serial.cpp
Merge pull request #4 from ziyangli/master

added include check
Merge pull request #1 from mavlink/master

sync with upstream