delete jetty 6.1.26 form spark package

In spark code, jetty version is 8.1.14.v20131031 (see ./pom.xml). But when building, the jetty-6.1.26 and jetty-util-6.1.26 is packaged in spark-assembly*.jar. So the version 8.1.14.v20131031 and 6.1.26 of jetty are existed in spark-assembly*.jar. 
When achieving SslSocketConnector using jetty in Spark web, this is a problem. Because jetty v6 dose not support sslContextFactory(), should make own SslSocketConnector . See: http://stackoverflow.com/questions/26382540/how-to-disable-the-sslv3-protocol-in-jetty-to-prevent-poodle-attack