Add logging capability (#175)

* Refactoring and addition of logzero (#172)

* Refactored convert.py and added logging.

* Added logging and refactored.

* Added logzero to requirements.txt

* Added logging to metadata.py

* Created a log in misc.py. Updated slugify import.

* Some general improvement

* Improve message layout

* Improve test mechanism

* Implement debug level logging

* Fix some minor mistakes

* Make pytest happy

* Remove unimplemented --verbose option

* Update ISSUE_TEMPLATE.md

* Rename LICENSE

* Remove obvious from log.debug()

* Show track URL when writing to file (debug)

core/logger.py

@@ -0,0 +1,16 @@
+import logzero
+import logging
+
+_LOG_LEVELS_STR = ['INFO', 'WARNING', 'ERROR', 'DEBUG']
+
+def log_leveller(log_level_str):
+    loggin_levels = [logging.INFO, logging.WARNING, logging.ERROR, logging.DEBUG]
+    log_level_str_index = _LOG_LEVELS_STR.index(log_level_str)
+    loggin_level = loggin_levels[log_level_str_index]
+    return loggin_level
+
+
+# Create a logger
+log_format = ("%(color)s%(levelname)s:%(end_color)s %(message)s")
+formatter = logzero.LogFormatter(fmt=log_format)
+log = logzero.setup_logger(formatter=formatter, level=logging.INFO)