Added plex.py

Added Plex input plugin. Uses a Plex media server tv-section as input.
PEP8
Nicer looking urlopen
Added myplex and selection support.
Added myplex login (really this time!) and selection.
Had to set username and password to blank by default.
Added video codec, audio codec, video resolution to filename.
New configguration parameters:
    'lowercase_title'   Convert filename (title) to lower case.
    'strip_year'        Remove year from title, ex: Show Name (2012) 01x01 => Show Name 01x01