[ANN] Legit Input Validation

[James Cunningham]

Hey Gophers!

Today I released my library to help with user input validation, called Legit. I would appreciate any and all feedback.

The difference between existing libraries which tend to use struct tags, Legit defines an interface requiring types have a method called `Validate` and exposes helpers for walking structs/slices with fields that contain a validator.

https://github.com/jamescun/legit

Thanks!