Common logging code

The ACL manager logs in a different format to Felix. That is quite annoying. Rather than let this fall out of step again, I decided that the best thing to do would be to commonalise the logging setup code for both products.

This means that the ACL manager and Felix now log in exactly the same way to the equivalent set of sources.

An optional extension would be to make the ACL manager's configuration file match the form of Felix's, thereby adding stdout and syslog level parameters to it.

Warning: I haven't had a chance to test this code, we may want to hold off on merging until we have more UTs to ensure that nothing breaks.