Logging and Tests

Here I address #5 (closed) and #4.

It would be useful if before confirming you could try the following as well, just to check that everything works as expected:

• after installing, run python -m unittest -v to run the only test I implemented
• try the four configurations to run run_taggers.py
  • run_taggers.py alone shouldn't do anything
  • run_taggers.py --log-level DEBUG should print one line of debug information
  • run_taggers.py --log-file output.log should produce an empty file called output.log
  • run_taggers.py --log-file DEBUG --log-file output.log should print debug information and print that same information in output.log

Unfortunately I didn't find a way to implement tests for scripts in a test suite. Probably it is something that we will have to implement in the CI.

Feedback about the README is also appreciated (whether it's clear enough, something should be added, etc.).