makefile wibbles
ivory-px4-tests: reimplement platforms in terms of ivory-bsp-tests platforms
ivory-px4-tests: disable copter motors for now

ar drone copter motors driver is pretty borked
more important to get sensors working properly
ivory-px4-hw: fix types in hmc5883l statemachine
ivory-px4-tests: hmc5883l test typechecks
ivory-px4-hw: formally remove motor control drivers from the build

re-enable them once we take time to fix them.
ivory-px4-tests: fixup types in ms5611 driver statemachine
ivory-px4-tests: doc wibble
ivory-px4-tests: MS5611 test app typechecks