py3: use raw strings while accessing class.__dict__ The keys of class.__dict__ are unicodes on Python 3.

py3: handle opts correctly for `hg add` opts in add command were passed again to cmdutil.add() as kwargs so we need to convert them again to str. Intstead we convert them to bytes when passing scmutil.match(). Opts handling is also corrected for all the functions which are called from cmdutil.add().