Does not use final mpd url for relative paths

Created by: LloydW93

Currently, if you have an MPD passed in that responds with a redirect, e.g. http://www.example.com/stream/manifest.mpd -> HTTP/1.1 302 Found http://www.example.com/dash/mainfest.mpd

Then relative URLs defined in the MPD will be relative to /stream, rather than /dash. This is a failure to follow https://www.ietf.org/rfc/rfc3986.txt section 5.1.3 and can cause problems with complex setups.

This case is simple to handle on all browsers except IE (currently), and I'll be submitting a pull request shortly to enable this.