More integration testing

[nphilipp]

Story

As a contributor to mirrors-countme,
I want that its basic functions are tested in a more integrated way,
so that I don’t just have to depend on unit tests (which might get things wrong when testing in isolation).

Acceptance Criteria

The commonly used functionsare tested in an integrated way, using synthesized test data which resembles the real deal:

• parsing logs ⇒ raw DB
• summarizing raw DB ⇒ totals DB
• trimming old data