Add loggers for project code to the log4j configuration files

The archetype has two log4j configuration files to the project: log4j-dev.xml and log4j-dist.xml.

There are no loggers defined for the project code, by default the org.example package. I think it makes sense to add these, like:

<logger name="org.example">
   <level value="debug"/>
 </logger>

The level for the -dev file should be "debug", for the -dist file it should be "info". The package name should not be hard coded, but taken from the parameters given when the project is created from the archetype.

Note: the notation for log4j 2 may be different than the example given here.