ArduCopter: fixes to allow AP_Mount to work on APM1 with original default...

ArduCopter: fixes to allow AP_Mount to work on APM1 with original default channels and fix to reenable support for 3-axis gimbals on APM2.

Channels 5 to 11 changed to RC_Channel_aux.
Removed channel 9 because APM_RC doesn't support it in any case.
Updated EEPROM format version to 119 because of the change to RC_Channel_aux and because k_param_rc_11 moved to be after k_param_rc_10.