Changes for AdvParameterList number display, and proper handling of CH6/7/8 options in ArduCopter pids

Change in implementation details for Camera Gimbal Config, usable now, but needs more error checking.

Added in checks for being connected to a MAV before attempting edits of configuration in Battery Monitor Config

Implementation of Battery Monitor configuration, and addition of AP2ConfigWidget, which automatically handles UAS connections to allow for simpler configuration window code.

Additional functionality for Flight Mode config, including highlighting of current PWM value on channel 5