Password checker

[stephlocke]

Add functionality for the password endpoint

https://haveibeenpwned.com/API/v2#PwnedPasswords

[maelle]

And add related tests.

[brooklynbagel]

This looks interesting if you're still looking for contributors.

[stephlocke]

Yup! @holisticinfosec has been working on this over on https://github.com/holisticinfosec/HIBPwned

Russ has a working solution but it either needs to be amended to work in base R or data.table be added as a dependency http://r-pkgs.had.co.nz/description.html#dependencies

Further, Russ could do with a hand on getting some unit tests written for the function.