added "if trained" to sampler mungebit
Merge branch 'truncator' of github.com:robertzk/mungebitsTransformations into truncator

* 'truncator' of github.com:robertzk/mungebitsTransformations:
  added tests to Discretizer FactorGaps
  changed discretizer to handle Unforseen FactorLevels within test(prediction)
  added stopifnot to make sure x is numeric