Fix the errors

These changes resolved the errors I got while running through the tutorial, and fixed some minor things I noticed along the way.

The big two are 63d5af0241e3875a7f74b2ddb8a9bf778c904880 Pull from the correct jetty branch and 7985bea252a3ab9ca2d3b8820961220c050dc62a Add file handling at the correct place in the controller.

There are three commits (b69d00fb16c7798619797dbde0084e65f5c193b8, 3196ffdf3a4ea39ff7019c8a36106921a4bdbc1d, and 993b002661799f0deb7bd55667a13e6404aca633) that replace NokogiriDatastream with OmDatastream, as I got deprecation warnings.

With these changes, I've been able to run the tutorial with hydra-head 6 from start to finish.