use jetty-client 9.3.11.v20160721
use jetty-client 9.3.11.v20160721

Includes fixes for some important proxy bugs:

* https://bugs.eclipse.org/bugs/show_bug.cgi?id=475546
* https://github.com/eclipse/jetty.project/issues/416
treasure-data/digdag,treasure-data/digdag,treasure-data/digdag,treasure-data/digdag,treasure-data/digdag,treasure-data/digdag,treasure-data/digdag