Create JMH benchmark viewer

JMH benchmarks results are saved to the gremlin-benchmark/benchmark directory in JSON format. It would be nice to have a simple way to view benchmark results side by side. Perhaps a simple index.html file with some javascript to view the results of runs side by side. JMH uses the method names to identify tests so that along with the test class name could be used to tie results from different runs together. This Jenkins plugin might have some interesting examples of visualization in it.