Added Post representation and the TimelineService plus corresponding test class.
Added println() method to TextDevice implementations. This is needed e.g. for timeline printing.
Added a specialised 'printer' logic for Posts.
PrettyTime shows also '1 second ago' now. Beside that, the timeline output is now in correct order (descending) and a corresponding test was added.
Small clean ups, import organising and TravisCI configuration copied, just to avoid possible merge errors.
Merge branch 'feature/posting' into develop

One can post message to a personal timeline now. As it was needed for testing, reading is also possible now.
Travis can build develop branches too, so he should it.