code: @SuppressWarnings("unchecked")
  	public static void registerValidator(Class<? extends IValidator<?>> validator) {
  		if (validator == null) {
  			throw new IllegalArgumentException("validator cannot be null");
  		}
  
  		ValidatorFactory.registerValidatorClasses(validator);
  	}
docs: Register custom validator. This is only usable if you want to use custom validation annotations.
  Otherwise you can use {@link eu.inmite.android.lib.validations.form.annotations.Custom} annotation.
  
  @param validator validator class that is annotated with {@link eu.inmite.android.lib.validations.form.annotations.ValidatorFor} annotation.
  @throws IllegalArgumentException if validator is null