doc(install): Install on Ubuntu Xenial

Guide kindly provided by Emmanuel Agliardi

docs/docs/INSTALL_ubuntu_xenial.rst

+Install Ravada - Ubuntu Xenial
+==========================
+
+It is advisable to install Ravada in one of the supported
+platforms: Ubuntu Bionic ( 18.04 ) or Fedora.
+But if you want to install
+in another distribution it can be done.
+
+Packages
+--------
+
+Install those packages:
+
+.. prompt:: bash $
+
+    sudo apt-get install perl libmojolicious-perl mysql-common libauthen-passphrase-perl \
+    libdbd-mysql-perl libdbi-perl libdbix-connector-perl libipc-run3-perl libnet-ldap-perl \
+    libproc-pid-file-perl libvirt-bin libsys-virt-perl libxml-libxml-perl libconfig-yaml-perl \
+    libmoose-perl libjson-xs-perl qemu-utils perlmagick libmoosex-types-netaddr-ip-perl \
+    libsys-statistics-linux-perl libio-interface-perl libiptables-chainmgr-perl libnet-dns-perl \
+    wget liblocale-maketext-lexicon-perl libmojolicious-plugin-i18n-perl libdbd-sqlite3-perl \
+    debconf adduser libdigest-sha-perl qemu-kvm libnet-ssh2-perl libfile-rsync-perl \
+    libdate-calc-perl libparallel-forkmanager-perl
+
+In addition you need one package that it still may not be in Ubuntu repository, download from our own server at the `UPC ETSETB
+repository <http://infoteleco.upc.edu/img/debian/>`__ and install it this way:
+
+.. prompt:: bash $
+
+    wget http://infoteleco.upc.edu/img/debian/libmojolicious-plugin-renderfile-perl_0.10-1_all.deb
+    sudo dpkg -i libmojolicious-plugin-renderfile-perl_0.10-1_all.deb
+
+
+These packages are required to build some dependencies from source:
+
+.. prompt:: bash $
+
+    sudo apt-get install gcc gcc-4.8 make libssh2-1-dev libnet-ssh2-perl libssh2-1 libdate-calc-perl zlib1g-dev libpcre3-dev zlib1g-dev libpcre3-dev
+
+Perl Modules
+------------
+
+Some Perl modules must be compiled from source:
+
+.. prompt:: bash $
+
+    sudo perl -MCPAN -we 'install "Net::SSH2"'
+
+Database and configuration
+--------------------------
+
+From now on you can follow the instructions for Ubuntu 18.04. Skip to
+the MySQL installation step.
+
+`Install Ravada in Ubuntu 18.04 <https://ravada.readthedocs.io/en/latest/docs/INSTALL.html>`__ .

docs/index.rst

@@ -56,6 +56,7 @@ Do you feel like giving us a hand? Here you have all the information you need as
 
    docs/INSTALL
    docs/INSTALL_Fedora
+   docs/INSTALL_ubuntu_xenial.rst
    docs/production
    docs/recomendations
    docs/INSTALL_devel