Replace eval() with JSON.parse()

[augustjanse]

Fixes #8. Not sure why the $.parseJSON() line was commented out, but apparently it is deprecated with jQuery 3.0, so I replaced both lines with its successor.

Error fixed:

Uncaught EvalError: Refused to evaluate a string as JavaScript because 'unsafe-eval' is not an allowed source of script in the following Content Security Policy directive: "script-src 'self' *.apple.com".


    at callbackFunction (<anonymous>:70:45)
    at XMLHttpRequest.xmlhttp.onreadystatechange (<anonymous>:63:47)

[augustjanse]

For the record, the eval() has been there since the script was imported.

[dufferzafar]

Thanks a lot @augustjanse