EPM apm2.x support

disabling the external leds with this is ugly and it does not work right. the 'leds' start to blink before we get here in the code
1249 in arducopter.pde
if(g.EPM_Enable)
	AP_Notify::flags.external_leds = false;
and the gpio pins for the other platforms should be defined AP_EPM.h

#elif CONFIG_HAL_BOARD == HAL_BOARD_APM1
 #define EPM_PIN_1   -1    // to be determine 
 #define EPM_PIN_2	 -1    // to be determine
#elif CONFIG_HAL_BOARD == HAL_BOARD_PX4
 #define EPM_PIN_1   -1    // to be determine 
 #define EPM_PIN_2	 -1    // to be determine
#else
 #define EPM_PIN_1   -1    // not supported
 #define EPM_PIN_2	 -1    // not supported

enjoy!