update to return FieldValidationError for single field validation
add Kind, Param and Value to the FieldValidationError struct to allow
for a more automated error handling api outside of this library.
add lt validation function + test code
add lte validation function + test code
add gt validation function + test code
add get validation function + test code
add rgb color validation function + Test Code
add rgba color validation function + Test Code
add hsl color validation function + Test Code
add hula color validation function + Test Code
add numeric validation function + Test Cases
add number validation function + Test Cases
add hexadecimal validation function + Test Cases
add hexcolor validation function + Test Cases
add email validation function + Test Cases
