Switched from a thread pool to a pre-fork system.
Switched from a thread pool to a pre-fork system.

 - Pillow is too CPU heavy to be efficiently passed arouned to the
   different CPU cores when the GIL is blocking us.  Switching to
   a thread pool system and setting up a work queue enabled us to
   make better.

 - Also fixed formatting to be consistent across the file.

redfin/dirpy