Upgrading to python3 (#60)

* Migrating to python 3.7.2, but docker image is not working properly.

Need to continue investigating why it's not properly running.

* Trying to fix the build and fixing logging in the scheduler initialization.

* Trying to fix the build

* Collecting test results

* Fixing the dockerfile

* Updating the development dependencies

cachet_url_monitor/scheduler.py

@@ -5,7 +5,7 @@ import time
 
 import schedule
 
-from configuration import Configuration
+from cachet_url_monitor.configuration import Configuration
 
 
 class Agent(object):
@@ -84,7 +84,7 @@ if __name__ == "__main__":
         handler.addFilter(logging.Filter('cachet_url_monitor'))
 
     if len(sys.argv) <= 1:
-        logging.fatal('Missing configuration file argument')
+        logging.getLogger('cachet_url_monitor.scheduler').fatal('Missing configuration file argument')
         sys.exit(1)
 
     scheduler = Scheduler(sys.argv[1])