[Feature] Handling g-recaptcha errors

[Streemo]

Current behavior (pseudocode):

if (captcha passed)
  redirect back to original page
else
  response.end('Captch verification failed!') //plain text
  return true;

Improved behavior (pseudocode):

if (captcha passed)
  redirect back to original page
else
  var thereWasAProblemHtml = Assets.getText('googleFailed.html')
  response.write(thereWasAProblemHtml) //html
  setTimeoutForBlockIpForMilliSeconds
    redirect back to original page
    res.end()
    return true;

This way, the user is not shown plain text when google messes up, and instead Sikka has a fallback (redirect in blockIpFor milliseconds). Currently, Sikka will end the response with plain text, forcing the user to manually try again.