Improves application's start screen to be more intuitive.

During the 2nd poster session we got feedback on the application's initial start page not always behaving as expected. E.g. most users pressed enter to locate themselves which leads to the form being reloaded instead of location data being fetched. This pull-request is concerned with improving issues related.

# Checklist
- [x] Bind enter key to trigger location search
- [x] Give feedback whether location was found or non-found
- [x] Redirect automatically in case location data is present
- [x] Merge master and merge back into master
- [ ] Reviewer approved code

Closes #69