Create configuration and database routing mechanism

[EliuX]

We need to externalize configuration, at least in Python classes. With them, we will be able to set up different variables for each context even if they seem not to change for the moment.
For instance, we need to be able to specify which database solution/driver we want to use without having to refactor the whole configuration. Although this database solution is pending of definition we should be able in this PR a mechanism to route to a specific one just by changing a value in the configuration.