Update style guide with new patterns defined

[juancarrey]

ACs:
Add interfaces definition for everything
Add types definitions for everything
Add constructor enforces data integrity of the class and well usage (early fail)
Add avoid NullChecks/UndefinedChecks (from above).

[javierlopezdeancos]

this style guide where should be leave? the wiki?

[juancarrey]

There is already one at styleguide.md https://github.com/Devnilson/fisima/blob/develop/styleguide.md