Update to add deb-multimedia-keyring and zlib1g
Update to add deb-multimedia-keyring and zlib1g

1. The http://www.deb-multimedia.org/pool/main/d/deb-multimedia-keyring
file keeps changing so changed to `sudo apt-get install -y --force-yes
deb-multimedia-keyring` after adding `deb http://www.deb-multimedia.org
jessie main` to `/etc/apt/sources.list`
2. Added `apt-get install zlib1g` to build python `lxml` package.

readbeyond/aeneas-vagrant,pettarin/aeneas-vagrant