Quick fix for Curse site handling.

Changed the way Curse site is parsed. Switch from string operations the HtmlAgilityPack so that you can walk the page as an object.
CurseForge handler supports more/better values.
Updating mods is broken.

This is a quick fix, need to rewrite anything that parses a website to use this, the move the XPATH search strings to a config file, so that when Curse chages their site again it doesn't require a recompile.