Use absolute value for LSQ regularization

L1 regularization should use the absolute value, not the real value, of the parameter to be kept small.
Least squares builder cleanup

Rearrange code to make Least Squares builder more readable
Rename least squares test

LSQ tests had wrong class name, so IntelliJ couldn't find them.
Merge pull request #624 from elehack/feature/elehack-lsq-fixes

Fixes and cleanups for the least-squares scorer