On previous implementation response code would only be collected for errors.
To avoid mixing new and old metrics, gave the one that includes successfull codes a different name
* Add support for Dropwizard Metrics 4.1.x
Dropwizard Metrics 5.x is currently unmaintained, so there should be the option
to use the currently maintained Dropwizard Metrics version.
* Reformat code
* Add dropwizard-metrics4 to README.md