Create an install script

We need a simple install script so we could just do on a new bare metal server :

curl get.libre.sh && bash libre.sh

To have a running environnement

-> The script should do the exact same steps of Install_Linux.md https://lab.libreho.st/libre.sh/compose.libre.sh/blob/master/INSTALL_LINUX.md

an extra step would be needed to setup global variables by editing the global environnement file