Add tslint.json as filename for JSON with Comments

[cedrickcooke]

Corrects handling of tslint configuration files.

Checklist:

• I am associating a language with a new file extension.
  • The new extension is used in hundreds of repositories on GitHub.com
    • Search results for each extension:
      • https://github.com/search?utf8=%E2%9C%93&type=Code&ref=searchresults&q=filename:tslint.json
  • I have included a real-world usage sample for all extensions added in this PR:
    • Sample source(s):
      • https://github.com/cedrickcooke/linguist/blob/tslint/samples/JSON%20with%20Comments/filenames/tslint.json
    • Sample license(s):
  • I have included a change to the heuristics to distinguish my language from others using the same extension.