Fixed engine/implement bus being assigned wrong
Made `isoblued` run in a single thread

Everything happens in a `select` now.
Optimizations/restructuring from profiling

The BeagleBone Black's processor maxes out:
* when both buses are full rate
* when one bus is full rate and Bluetooth is connected
Added more testing tools

* `can_stress` puts full load on CAN bus(es)
* `isoblue_dummy` replaces Android library in testing
Fixed bottleneck responsible for problem in 4261964849294a52c1e6a2d0aec6f585c06b7050

BeagleBone Black is now able to receive full rate on both CAN buses,
and send it all over Bluetooth (uses *almost* all the CPU).

Changed how messages were put in the buffer,
so that they could be taken out more easily/quickly.
Improved reliability of isoblue systemd service

* Starts up first try now
* Moves buffer file to disk on stop
* stops can-log service from running on same RFCOMM channel
Improved help/usage messages for `isoblued`
Merge pull request #10 from awlayton/master

I believe ISOBlue will work with the library for real now