NUTCH-3137 Upgrade Nutch core dependencies

Roll back to RAT 0.16,
address build failure caused by new RAT report format.

Author: sebastian-nagel

build.xml

@@ -44,7 +44,7 @@
   <property name="spotbugs.home" value="${ivy.dir}/spotbugs-${spotbugs.version}" />
   <property name="spotbugs.jar" value="${spotbugs.home}/lib/spotbugs-ant.jar" />
 
-  <property name="apache-rat.version" value="0.17" />
+  <property name="apache-rat.version" value="0.16" />
   <property name="apache-rat.home" value="${ivy.dir}/apache-rat-${apache-rat.version}" />
   <property name="apache-rat.jar" value="${apache-rat.home}/apache-rat-${apache-rat.version}.jar" />