Forgot to copy the readme.txt for RedditImageGrab.
Bugfix in urlopen() encoding.

In python 2, urlopen() returned a string, in python 3, it returns
a byte object that had to be converted first.
Changed interface of redditdownload.py.

Moved the download functionality into a separate function that can
be called independently and added some one options not used in the
command line interface (quiet).