Clear job queue when reloading

Just a stop-gap to make #831 not a regression so 6.0 can get out the
door. It's not the right solution, but it's slightly better than what
was there before. Only reloading a module with a job actually in it will
kill all the jobs now, rather than any module. So, progress?

sopel/bot.py

@@ -162,7 +162,9 @@ def unregister(self, obj):
             for rule in obj.rule:
                 self._callables[obj.priority][rule].remove(obj)
         if hasattr(obj, 'interval'):
-            pass  # TODO
+            # TODO this should somehow find the right job to remove, rather than
+            # clearing the entire queue. Issue #831
+            self.scheduler.clear_jobs()
         if getattr(obj, '__name__', None) == 'shutdown':
             self.shutdown_methods.remove(obj)