Performs a http request using the specified parameters and returns the http response in a callback.
PerformHttpRequest(string url, function callback[, string method = 'GET', string data = '', table headers = {}])
PerformHttpRequest("http://some-cool-url.here/some-important-document.txt", function (errorCode, resultData, resultHeaders, errorData)
print("Returned error code:" .. tostring(errorCode))
print("Returned data:" .. tostring(resultData))
print("Returned result Headers:" .. tostring(resultHeaders))
print("Returned error data:" .. tostring(errorData))
end)