d/gestioip: add basic apache2 config file

This commit adds a very basic apache2 config file.

In the config file, GestioIP files are server from /usr/share/gestioip,
and this is likely violating some Debian guidelines.

The apache2 config file is /etc/gestioip/apache2.conf, which is symlinked
in postinst to /etc/apache2/conf.d/gestioip.conf, as seen in other Debian
packages (ie mediawiki).

Anyway, we want to revisit this again. Eventually, we may include config
for nginx, lighttpd and others friends.

Signed-off-by: Arturo Borrero Gonzalez <arturo.borrero.glez@gmail.com>