Ubuntu: Add Media now upload files into Library

With a fresh install of Ubuntu 14.04.1 LTS Trusty and Airtime 2.5.1-5, the "Add Media" feature silently fails because the /etc/airtime/airtime.ini file is not parsed by Apache PHP.

While with Debian (at least on my 7.7 Wheezy) "libapache2-mod-php5" package, the path "/etc/php5/apache2/conf.d" is just a symlink to "/etc/php5/conf.d", it seems that with Ubuntu's "libapache2-mod-php5" it's a real folder on its own.

Therefore, current installation of Airtime on Ubuntu 14.04.1 get an "Add Media" feature which silently fails, as noted by Stefan here: https://forum.sourcefabric.org/discussion/comment/27548#Comment_27548 (though it was for Ubuntu 13.10).

A way to fix this (which should work both for Debian and Ubuntu) is to directly create the "airtime.ini" symlink into "/etc/php5/apache2/conf.d", as suggested in the pull request.