Remove the useless FreeRTOS demo
Merge branch 'free_rtos' of https://github.com/fboris/QuadrotorFlightControl
Add the flight control task and start using FreeRTOS

*The flight control task should be separated into different parts to let the structure more clearly
Remove FSM related code
Finish adjusting the code of System init and Status report
Create the Flight control task which is porting from Systick_handler()
Set the NVIC Priority Group to NVIC_PriorityGroup_4
Set the priority of FlightControl_Task to be the highest
Merge pull request #20 from shengwen1997/master

Finish creating the basic required tasks