support logging levels through Java-implementation of pxi:message

fixes daisy/pipeline-issues#335
replaced cx:message references with px:message
added common-utils to validation-utils catalog
moved pxi:message to public namespace as px:log-message

also updated to use the new BOMs
Namespace and import cleanup
Merge pull request #60 from daisy/pxi-message-java-implementation

Java-implementation of pxi:message