Removed logback usage from classpath
Added slf4j-log4j12 dependency in nifi-toolkit pom
Added logback-classic exclusion for nifi-properties-loader used by nifi-toolkit-encrypt-config
Updated log4j.properties logging pattern and logger config in nifi-toolkit-assembly and nifi-toolkit-zookeeper-migrator, filtering zookeeper messages below WARN
Removed logback.groovy since log4j is the single logging implementation
Updated ZooKeeperMigratorMain command line output to match standards established by other tools in nifi-toolkit
This closes#1237.
Signed-off-by: Andy LoPresto <alopresto@apache.org>
