function isEmptyString( value ) {
	return (
		isString( value ) &&
		value.valueOf() === ''
	);
}
Tests if a value is an empty string object.

@param {*} value - value to test
@returns {boolean} boolean indicating whether value is an empty string object

@example
var bool = isEmptyString( '' );
// returns false

@example
var bool = isEmptyString( new String( '' ) );
// returns true

@example
var bool = isEmptyString( [] );
// returns false