log4j - set different loglevel for different packages/classes

Instead of using 'category' use 'logger'. Hence, these level are configured for entire log4j, and does not depend on appender, etc.

Following change works:

log4j.logger.my.pkg=info
log4j.logger.my.pkg.ab.class1=debug

Copying from my current log4j.properties:

log4j.logger.org.hibernate.tool.hbm2ddl=warn
log4j.logger.org.hibernate.sql=info