Compass Tests V2

Ok once again I just want to use this PR to discuss some stuff. It's in no way ready to merge

https://github.com/rwaldron/johnny-five/issues/200
Thanks. Will also be nice to know that I haven't  messed up and that they both point to the same north (not sure if iPhone points to magnetic or true north). I still have a bit of work to do with the tests but I should be done soonish.