Add debug logging for CLI arguments

[stefan6419846]

This change adds debug logging to see which CLI arguments pytesseract passes to Tesseract itself. The goal is to simplify debugging reported issues, especially as most of them turn out to be related to plain Tesseract anyway, fixing the first part of #456.

Example usage

import pytesseract
import logging

logging.basicConfig(level=logging.WARNING)
logging.getLogger('pytesseract').setLevel(logging.DEBUG)

image = '/home/stefan/Desktop/file.png'
print(pytesseract.image_to_string(image))

Example output

DEBUG:pytesseract:['tesseract', '/home/stefan/Desktop/file.png', '/tmp/tess_0kncj5u3', 'txt']

This is my text.

[bozhodimitrov]

PS: This will require a new release. I will try to create it whenever I have some time.
Thanks for your time for improving and helping with the project.