Firefox only asks me to download the file's source. View-source shows me source code.
a2enmod php7.0
Considering conflict php5 for php7.0:
Module php7.0 already enabled
php -v
PHP 7.0.8-0ubuntu0.16.04.2 (cli) ( NTS )
Copyright (c) 1997-2016 The PHP Group
Zend Engine v3.0.0, Copyright (c) 1998-2016 Zend Technologies
with Zend OPcache v7.0.8-0ubuntu0.16.04.2, Copyright (c) 1999-2016, by Zend Technologies