Nearest neighbor test app

Added nearest neighbor localization class
Only does one neighbor at the moment
Weighted average of results, unit test, out-of-range

predictKnn() takes any value of k and computes a weighted average of all
the points
Added some unit tests, with a fake beacon manager and fake beacon for
simulation purposes
Added out-of-range considerations so the sampling won't waste time
waiting for out-of-range beacons