Solve all flake8 warnings (#163)

Whipper is now fully PEP8 compliant.
Revised version which includes all the changes suggested by Freso.

whipper/program/flac.py

@@ -3,6 +3,7 @@ from subprocess import check_call, CalledProcessError
 import logging
 logger = logging.getLogger(__name__)
 
+
 def encode(infile, outfile):
     """
     Encodes infile to outfile, with flac.