Moved command line parsing to args4j, removing the need for a custom jar...

Moved to args4j, getting a nice info like this:

$ java -jar target/johanna-1.0.0-SNAPSHOT.jar --help
 --backend (-b) [MEMORY | REDIS] : The session storage backend to use
 --debug                         : Whether to log with DEBUG level
 --help                          : This command line help
 --host (-h) IP                  : The IP of the REDIS server to bind to (see
                                   --backend, defaults to 127.0.0.1)
 --identifier (-i) [MD5 | UUID]  : The identifier factory to use
 --port (-p) N                   : The TCP/IP port to bind to

This is the single commit version as requested in #4