1. Have the RMSMappingQuality annotation take into account the fact that reduced reads represent multiple reads.
2. The rank sume tests should not be using reduced reads (because they do not represent distinct observations).
3. Fixed a massive bug in the BaseQualityRankSumTest annotation! It was not using the base qualities but rather
the read likelihoods?!
Added a unit test for Rank Sum Tests to prove that the distributions are correctly getting assigned appropriate p-values.
Also, and just as importantly, the test shows that using reduced reads in the rank sum tests skews the results and
makes insignificant distributions look significant (so it can falsely cause the filtering of good sites).
Also included in this commit is a massive refactor of the RankSumTest class as requested by the reviewer.
e48f754478