function toBinaryString( x ) {
	var b;

	// Convert the input value to a bit string:
	b = div2( x );

	// Left pad the bit string to ensure 8 bits are represented:
	b = lpad( b, NBITS, '0' );

	return b;
}
Returns a string giving the literal bit representation of an unsigned 8-bit integer.

@param {uinteger8} x - input value
@returns {BinaryString} bit representation

@example
var a = new Uint8Array( [ 1 ] );
var str = toBinaryString( a[0] );
// returns '00000001'

@example
var a = new Uint8Array( [ 4 ] );
var str = toBinaryString( a[0] );
// returns '00000100'

@example
var a = new Uint8Array( [ 9 ] );
var str = toBinaryString( a[0] );
// returns '00001001'