TRUNK-5114 Using different logging implementations instead of facade
we exclude the apache commons-logging dependency coming from springframework
and configure the slf4j facade with the log4j implementation but still
use commons-logging or log4j directly.
* replace usages by using the slf4j facade
* add "org.apache.commons.logging" to checkstyle's IllegalImport rule
so we get notified of anyone trying to use it
* replace log.fatal("message", exception)
