Cover 101companies:System with some modest bits of modeling

[rlaemmel]

At this stage, there is very little modeling.

Probably this is the only contribution based on (UML-like) modeling:

http://101companies.org/wiki/Contribution:argoUML

Some different cuts of models would be certainly useful.

We want to cover these kinds of diagrams:

• More options regarding class diagrams.
• Some behavioral models based on sequence diagrams, for example.
• A model at the level of use-case diagrams.

A basic challenge is to figure out some set of models in a way that they nicely complement each other as opposed to having a huge model once and for all.