[SPARK-6365] jetty-security also needed for SPARK_PREPEND_CLASSES to work

https://issues.apache.org/jira/browse/SPARK-6365

thanks vanzin for helping me figure this out

Author: Imran Rashid <irashid@cloudera.com>

Closes #5052 from squito/fix_prepend_classes and squashes the following commits:

09d334c [Imran Rashid] jetty-security also needed for SPARK_PREPEND_CLASSES to work

core/pom.xml

@@ -414,7 +414,7 @@
               <overWriteIfNewer>true</overWriteIfNewer>
               <useSubDirectoryPerType>true</useSubDirectoryPerType>
               <includeArtifactIds>
-                guava,jetty-io,jetty-servlet,jetty-continuation,jetty-http,jetty-plus,jetty-util,jetty-server
+                guava,jetty-io,jetty-servlet,jetty-continuation,jetty-http,jetty-plus,jetty-util,jetty-server,jetty-security
               </includeArtifactIds>
               <silent>true</silent>
             </configuration>