Add @hnrch02 to `contributors` in package.json

@hnrch02 has kindly agreed to take over as Bootlint's BDFL going forward.
Since Bootlint now has all the essential features I can think of, has a good number of lint checks, has decent docs, and has its project infrastructure all set up (build scripts, CI, unit tests, code coverage, npm module), I feel comfortable handing over the reins and leaving the project in @hnrch02's capable hands. And importantly, we both agree that semicolons are mandatory :-)

FYI: @zacechola ([grunt-bootlint](https://github.com/zacechola/grunt-bootlint)'s maintainer)