Changes:
* Show warnings for JsonCsrtf attacks.
* do not enable parameter escaping by default, fixes#8.
* Use more specific namespace declaration in Rack::Builder configuration.
* NotimpelentedError typo fix
* add test that makes sure passingin on :track option works. related to #6.
* deal with PATH_INFO being nil, fixes#7.
* do not track HTTP_VERSION, fixes#6.