Changed bundling

* Added js.jar of Rhino 1.7R5pre
  (from github master: https://github.com/mozilla/rhino/commit/013a3ef676ab9424fc2229a33026b085e069b2cb)
* Added js-engine.jar of JSR-223 script engine on Rhino
    * Built with a instruction described at
      https://wiki.openjdk.java.net/display/Nashorn/Using+Rhino+JSR-223+engine+with+JDK8
* Removed bundled JRE7u71
    * From now, use the latest JRE installed on the client machine
Updated README.md