Remove leaflet-rails gem and replace it with vanilla leaflet assets.

The leaflet-rails gems I tried don't work in server less JS testing scenarios because either
- they use *.erb-files, which are not processed in this context.
- they use relative pathnames for their assets.
Add vendored javascript to src directories. (This is required for leaflet).
Frontend: Refactor places module – use controller as mediator to decouple the components.
Frontend: Refactor places module – use controller as mediator to decouple the components.
Merge branch 'refs/heads/feature/jasmine-tests' into prototype