Change Details

**Problem:** Setting up Kartotherian locally was tricky on my Ubuntu machine, Node versions and dependencies such as Mapnik etc made it a pain. On the other hand running the tests with `docker run -p 6533:6533 kartotherian` worked out of the box. **Idea:** Would it be possible to setup an image for the host environment and one for the application/tests and only have the second one rebuilt whenever you have made changes to the code? Also would it be possible to make this work with local instances of some of the many npm dependencies(what you would usually have `npm link` for)? **Impact:** It could lower the barrier for new contributors.