Thrust allocator output

[Jared-Chan]

In the triton_controls package, change the thrust_allocator node so that the signals publisher publishes appropriate messages for the Teensy thruster controller.

An example of the correct signal format is in the key publisher.

The signal should be an unsigned 32-bit integer. The first 30 bits are divided into continuous groups of 5 bits, each group representing the power level of a thruster. Power levels range from -16 to 15.

The README in triton_teleop contains more information on the naming convention of thrusters used in the key publisher.