Remove some useless "confidence" stuff (#1895)

* Remove some useless "confidence" stuff

- HHVM implies PHP
- Mattermost can run on Postgre or Mysql, there is no point in showing them both at 50%, we don't do this for anything else
- If something is powered by ASP.NET, it's running ASP.NET
- If there is "Python" in a "Server" header, it's powered by Python
- RiteCMS is running on SQLite by default, it's the whole point of running this CMS instead of something more heavy
- JQuery is a mandatory dependency of typeahead

* @q-- is right, HHVM might imply Hack

I haven't seen any serious website in Hack, except facebook,
so lets go for 75%

* @q-- is right again

> Microsoft IIS will send this header if ASP.NET is installed (by default if you use IIS, I think) even ASP.NET isn't actually used.