Update en_US.php

Some linux distribution support qupzilla-qt5 package in official repos.
[FIXME] Added command for install qupzilla-qt5-git

Version based on Qt5 in Arch Linux repos now.
Update en_US.php

FIX FIX FIX
Update download.php

Fixed.
Merge pull request #9 from AlexTalker/patch-2

Patch for Acrh