Integration tests

[hiddewie]

Add test cases for web and tiles

Fixes #86

Tasks:

• Download a small piece of OSM data (Berlin is already cached from the API tests)
• Import the data, verify import succeeded
• Generate tiles, verify tiles build
• start martin-cp and verify tile requests work
• Start Martin
• Start API
• Start proxy
• Run web browser tests, viewing the page, making screenshots, searching and asserting some basic things on the screen.
• Reuse built artifacts