PHPCRED-39: Utility script for viewing audit logs

Would like to create a small utility script for viewing/filtering and clearing the internal audit logs.

Should take command line arguments (no argument == print usage) and support the following

- view all logs (--view)
- clear logs (--purge)
- filter by username (--user <s>)
- start date (--start <d>)
- end date (--end <d>)
- filter by type (--type <n>)
- sort order (--sort ASC/DESC default ASC)

Would probably be wise to add a translation method to the core logging class so that it can be used to take the DB log format and translate it into something human readable (though the option to extract the raw format should also be available).

The audit-by-email plugin contains a basic translation module so that can likely be used.