function isKebabcase( value ) {
	return ( isString( value ) && kebabcase( value ) === value );
}
Tests if a value is a string in kebab case.

@param {*} value - value to test
@returns {boolean} boolean indicating whether a value is a string in kebab case

@example
var bool = isKebabcase( 'beep-boop' );
// returns true

@example
var bool = isKebabcase( 'Beep-boop' );
// returns false

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

@example
var bool = isKebabcase( 1 );
// returns false