Add Brett's ContaminationTrimmer

[git-p4: depot-paths = "//depot/private/jchin/HBAR-DTK/": change = 121802]
   remove Utils.py dependency

[git-p4: depot-paths = "//depot/private/jchin/HBAR-DTK/": change = 121803]
   minor update for readme

[git-p4: depot-paths = "//depot/private/jchin/HBAR-DTK/": change = 121804]
Add Brett's Vector trimming into the collection. We will need some refactoring
for all script to get some coding style consistency someday.