Systemd files to start sharelatex services

Each service is described in its own file.
Some services needs redis and mongodb to be
launched in order to open the connection
to those services.
We assume that texlive 2014 has been installed
in /usr/local/texlive/2014/bin/x86_64-linux.
stderr and stdout are sent to the syslog daemon
facility. Each service has it's own identifier
formed by a string sharelatex-SERVICE where
SERVICE is chat, web, clsi, docstore...
rsyslog configuration file.

This file defines a template (ShareLatex) and a
property based filter. When message are sent to
the syslog daemon facility with the appropriate
identifer string (ie sharelatex-SERVICE) the
file /var/log/sharelatex/sharelatex-SERVICE.log
is filled with messages from SERVICE service.
SERVICE is one of chat, clsi, web, filestore...