Solo-1.5.4: Update parameter defaults for consumer solo

Updated FS_BATT_CURR_RTL from 30 to 22. The consumer Solo uses less power than site scan solos, so this value needed to be lowered.

Updated GND_PRESS_MIN from 80000 to 50000. This will allow the solo to arm at higher altitudes. The heavier consumer solo needed this restriction since it did not have enough power to fly safely at higher altitudes. The consumer Solo is lighter and can handle it.

The ArduCopter-v2.px4 file for version 1.5.4 is attached to this release.