Fixes a NaA bug by casting rulesets to an array.

This fixes the `array_merge(): Argument #1 is not an array` error that arises when your ruleset key is called but doesn't exist or returns a null value instead of an empty array.
Merge pull request #93 from dalabarge/patch-1

Fixes a NaA bug by casting rulesets to an array.
Skip validation from being performed twice (#90)