adding tag "_jsonparsefailure" for failures in json-codecs

I've added the tag "_jsonparsefailure" in the codecs "json" and "json_lines" in case of parsing errors. So it's possible to filter out failed parsed json events and fix possible bugs in the input data.

Unfortunately I'm no ruby guru and i had problems to run the tests, but I've tested my changes by adding the files into the latest version (1.3.3) and it worked fine.