[JS] fixed endianness of input/output float operations

The Endianness was backwards for floating point operations in Input/Output. I have reversed the order. Run this test in JavaScript to verify:

	var output = new BytesOutput();
	output.bigEndian = true;
	output.writeDouble(1);
	var b = output.getBytes();
	trace(b.toHex());   //Outputs "000000000000f03f" should be "3ff0000000000000"