Fix an issue with File::label remapping numeric 'subject' unnecessarily

If 'subject' is set, but 'label' is not set, before remapping subject
to an integer, check if it is already a number. In this case, no
remapping is necesasry, and in fact remapping caused problems when
evaluating regression output
Make Pipes behave consistently between training and enrollment

When training transforms involving pipes, and projecting from one
stage to the next, break the training data into single item
templatelists (similarly to what is typically done by Distribute
transforms durign training). This allows e.g. ExpandTransform to work
as expected.
Use File::subject rather than acccessing the property directly
Updated gender classification model to fix label lookup
Merge pull request #46 from biometrics/label_subject_things

Address some issues with classification and regression