install "all contributors" support

[jimkring]

https://allcontributors.org/

[jimkring]

@all-contributors add @jimkring for code, test, and maintenance

[allcontributors]

@jimkring

I've put up a pull request to add @jimkring! 🎉

[jimkring]

@all-contributors add @jg-code for code and maintenance

[allcontributors]

@jimkring

I've put up a pull request to add @jg-code! 🎉

[jimkring]

@all-contributors add @tcplomp for code and maintenance

[allcontributors]

@jimkring

I've put up a pull request to add @tcplomp! 🎉

[jimkring]

@all-contributors add @RolfKal for test and code

[allcontributors]

@jimkring

I've put up a pull request to add @RolfKal! 🎉

[jimkring]

@all-contributors add @tmaila for code

[allcontributors]

@jimkring

I've put up a pull request to add @tmaila! 🎉

[jimkring]

@all-contributors add @justingoeres for code
@philippe-guerit

[allcontributors]

@jimkring

I've put up a pull request to add @justingoeres! 🎉

[jimkring]

@all-contributors add @philippe-guerit for code

[jimkring]

done

[allcontributors]

@jimkring

I've put up a pull request to add @philippe-guerit! 🎉