Added howlingAbyss map.
Merge branch 'master' of https://github.com/danielsuter/tank-wars

Conflicts:
	src/main/java/ch/tankwars/game/Game.java
Merge branch 'master' of https://github.com/danielsuter/tank-wars

Conflicts:
	src/main/java/ch/tankwars/game/Game.java
	src/main/java/ch/tankwars/game/RandomPositionCalculator.java
	src/main/java/ch/tankwars/game/Tank.java
	src/main/java/ch/tankwars/game/powerup/strategy/RandomPowerUpStrategy.java
	src/main/java/ch/tankwars/game/projectiles/Projectile.java
	src/test/java/ch/tankwars/game/GameTest.java
	src/test/java/ch/tankwars/maps/MapWriterTest.java
Merge branch 'master' of https://github.com/danielsuter/tank-wars