Add DatabaseWriter Module to Store Data in PostgreSQL

I added a new module called DatabaseWriter. It is switched off by default, since it requires previous installation of postgreSQL. This module manages the output into a postgreSQL relational database, which is useful for applications where fast real-time I/O is needed (e.g. external visualizers or real-time analysis). I also added a script in /etc/scripts/ which can be used to generate the database (one time action). The README should contain all the information needed to understand how to instantiate the module in the configuration file. Also, it quickly describes the structure of the database and gives basic instructions on how to create it and enable users to interact with it.