Decode IMDB API output as utf-8

I noticed that .movie sometimes generates a UnicodeDecodeError
exception, e.g. issuing '.movie gravity' produced:

  UnicodeDecodeError: 'ascii' codec can't decode byte 0xc3 in position
  151: ordinal not in range(128) (file "willie/modules/movie.py", line 26,
  in movie)

Adding an explicit 'utf-8' to u.decode() on the IMDB API result resolves
the issue for me.
Merge pull request #470 from rameshdharan/master

Decode IMDB API output as utf-8