I've changed the fetching of "hostUrl" variable to match not only domain, but the subfolder as well. The thing is I've installed the analytics to subfolder "/myfolder/" but when I used the code, the tracker tries to send the data to "mydomain.com/api/collect" instead of correct "mydomain.com/myfolder/api/collect". This change fixes the issue. It's not pretty to filter out the name of the script from the path by .replace, but I wasn't able to find better solution to get the subfolder. If you do, please change it :)
