Started implementing flights.
Service method to find flights for a player.
Added flight direction.
Flights can be finished.
Improved logging.
Improved demo data.

- Renamed moe to player1
- Created player2
- player1 sends a Mosquito to player2
Moved build time and resource cost from ShipService to ShipType enum.
Removing and restoring ships when starting a flight / returning a flight.
Added TODO entries.
Added service method to manifest ships on a planet.

- Refactored flight handling code.
Added ability to colonize planets.
A flight now has a start and destination location instead of planet ids.
Bugfixes for planet colonization.
Added Ships class for easier calculation of ship numbers.
REST endpoint for viewing flights originating from a planet.
Moved flights into an own resource.
Less boilerplate code for DI service module.
Added REST endpoint to start flights.
Merge pull request #2 from phxql/feature/flights

Feature/flights