Add .all-contributorsrc as JSON

[spenserblack]

This adds .all-contributorsrc as JSON. Link to documentation describing this file as JSON

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://cs.github.com/?scopeName=All+repos&scope=&q=path%3A.all-contributorsrc
  • I have included a real-world usage sample for all extensions added in this PR:
    • Sample source(s):
      • all-contributor's own .all-contributorsrc file
    • Sample license(s): MIT
  • I have included a change to the heuristics to distinguish my language from others using the same extension.

[Alhadis]

I think we can trim the contributors array down to only a few entries. The entries are mostly homogenous, so our classifier isn't really benefiting from the repetition.

[spenserblack]

Wow, thanks for the quick response! I was a little unsure about this because, while certainly real-world, it did feel overboard. So would you say about 3 would be enough?

[Alhadis]

Yep, 3's plenty. 👍

[Alhadis]

@lildude Usage checks out. Code search reports ~6,200 results; pretty damn sure there's at least 200 different users among those results.