New Post: Unique Value Validation

@TetleyK and @JeremyS.. see this: https://gist.github.com/Ridermansb/22239f8fce8d0f58f71b

I know that this error is not related to FluentValidation, but as this code may be useful to other developers thought if you could help me.
The idea is to create a generic PropertyValidator that works with any property.