enable apache2 rewrite_mod on ubuntu14.04

$ cd /etc/apache2/mods-enable
$ ln -s rewrite.load ../mods-available/rewrite.load
 change "AllowOverride None" to "AllowOverride All" in apache2.conf in 
<Directory /var/www>
        Options Indexes FollowSymLinks
        AllowOverride All
        Require all granted
</Directory>