Fixed js response output

[bakhangildin]

I figured out following thing:
String.fromCharCode(0) returns "\x00", but putstr and console.log borks there and not printing this symbol.
So i decided to hex encode everything

Also I made some investigation:
Implementation of putstr of spidermonkey https://github.com/ricardoquesada/Spidermonkey/blob/master/js/src/shell/js.cpp#L1555
I guess the thing that breaks everything on line 1561:

1561 if (!str)
1562     return false;