Various stylistic fixes

- Fix PEP8's line too long warning
- Remove useless parentheses
- Use triple quotes for docstring
- Address pylint's 'inconsistent-return-statements'
- Specify string format arguments as logging function parameters
- Comment out already disabled block of code
- Remove useless else (after return)
- Remove useless statement
- Do not import already imported module

whipper/program/utils.py

@@ -28,7 +28,7 @@ def unmount_device(device):
     If the given device is a symlink, the target will be checked.
     """
     device = os.path.realpath(device)
-    logger.debug('possibly unmount real path %r' % device)
+    logger.debug('possibly unmount real path %r', device)
     proc = open('/proc/mounts').read()
     if device in proc:
         print('Device %s is mounted, unmounting' % device)