Lots of changes to freshair.py. Added in multiprocessing functionality with non-daemonic
Many changes to freshair.py. For one, added functionality to programmatically
Download all Fresh Air episodes in a given year to a directory, excluding those
episodes that have already been downloaded. Using magic I found from stack
overflow at http://stackoverflow.com/a/8963618/3362358, to use the multiprocessing
module to allow for workers in a multiprocessing pool to spawn their own processes.