The main aim here is to remove log4j and main
classes from compile scope in the core library.

This will help integrate ethereumj-core as a library
into projects that don’t choose to use log4j and
want to use a different logging framework to back
slf4j.


Problems encountered:
`org.ethereum.util.AdvancedDeviceUtils` uses log4j
to dynamically change the logging config. There was
no resolution other than to remove this.

the build task needs `mainClassName` to be defined