get rid of erroneously-merged predictor math helpers on assignment model
get rid of erroneously-merged predictor math helpers on assignment model

mkoon/gradecraft-development,UM-USElab/gradecraft-development,UM-USElab/gradecraft-development,UM-USElab/gradecraft-development,UM-USElab/gradecraft-development,mkoon/gradecraft-development,mkoon/gradecraft-development