[NIFI-194] get mvn clean package working correctly
 - Removed phase definition for maven-source-plugin
 - Changed goal to jar-no-fork to prevent life cylcle forking
 - Removed version ranges.
[NIFI-195] Take advantage of inheritance from ASF parent version 16
Merge branch 'NIFI-194' of https://github.com/khmarbaise/incubator-nifi into develop
Merge branch 'NIFI-195' of https://github.com/khmarbaise/incubator-nifi into develop