rules: refactor Rule#apply_rule a little
rules: refactor Rule#apply_rule a little

Since I had to touch Rule#apply_rule anyways (previous commit), I just
made a small change to how the rules hash is built. Does not seem to
break anything (passes the rule specs), and reads better :).

svs/mostfit-private,Mostfit/mostfit,Mostfit/mostfit,svs/mostfit-private