bump jarjar plugin version

This fixes a packaging problem described in #434. It is a cleaner fix than the fix applied in that PR.

Author: jeanbza

pom.xml

@@ -402,7 +402,7 @@
         <plugin>
           <groupId>org.sonatype.plugins</groupId>
           <artifactId>jarjar-maven-plugin</artifactId>
-          <version>1.5</version>
+          <version>1.9</version>
         </plugin>
         <plugin>
           <groupId>org.apache.maven.plugins</groupId>