Augment data with information from a q_matrix object

Augment for q_matrix accepts a model object and a dataset and adds Q values to each observation in the dataset. Q values are stored in separate columns, which is given name with the pattern ".Q1",".Q2", etc. For consistency with broom::augment.prcomp, a column ".rownames" is also returned; it is a copy of 'id', but it ensures that any scripts written for data augmented with broom::augment.prcomp will work out of the box (this is especially helpful when adapting plotting scripts).