[misc] Made the plugin work both with Maven 3.0 and 3.1+
Exclude commons-logging from the classpath
Fixed warning generated by Maven 3.1+
[cleanup] Extracted utility methods into separate utility classes
Issue #1: Make the plugin work on Maven 3.1+
Fixed verbose logs printed while running the xarimporter on Maven 3.1+
Issue #2: The xar importer fails if executed again on the same project without cleaning
Fixed.
[misc] Better documentation