EXIF extraction not working via GUI processing

[johnhbenetech]

Processing via terminal with extract_exif works as expected.

However, running the processing through the GUI does not seem to extract the EXIF data

[johnhbenetech]

@stepan-anokhin I believe this fix has broken the terminal processing flow. when trying to run 'extract_features.py' I get the following error:

(winnow) tf-docker /project > python extract_features.py 
Traceback (most recent call last):
  File "extract_features.py", line 7, in <module>
    from winnow.pipeline.luigi.exif import ExifTask, ExifFileListFileTask
ImportError: cannot import name 'ExifFileListFileTask'