Improve Benchmark Suite

[tjcelaya]

There were some out-of-band discussions about improvements to the benchmark module which were being worked on but not yet tracked. These include:

• Splitting the java-manta-benchmark module into micro and macro projects. The module currently houses JMH micro-benchmarking code alongside an executable class which performs macro-benchmarking of MantaClient performance. Execution of benchmarks is not currently tied to any maven goal so existing benchmark code is more likely to go unnoticed
• incorporating douglasAtJoyent/JMeterMantaExtension into this repo for the macro benchmark functionality. That project already benchmarks the same functionality as the com.joyent.benchmark.Benckmark class and jmeter-maven-plugin can be used to export benchmarking results alongside test coverage reports