added original value to uniqueness validations

[dannysperry]

Added original_value to the data-validate uniqueness hash on the element
Added the original value to the proper areas in the Validator/Validation Ruby classes

Validation#validate! only runs rails validate_each method if the validation isn't a uniqueness validator that has a value equal to the original value and if the original value in those cases isn't an empty string(because we don't care about uniqueness on empty inputs)

[dannysperry]

@joecorcoran my OSS experience is limited, but its my understanding that we don't merge our own PR's. Let me know you're thoughts on how you want to handle this.

[joecorcoran]

Only a tiny thing but I'd like to maintain the style of using === in JS when testing for equality, and using == only when you need/want the ambiguity. It doesn't affect things at all in this case but it's a good habit to develop.

[joecorcoran]

Aside from the little note above this looks great, thanks @dannysperry, please merge! Agree that PRs need a second look wherever possible.