implement Tile.hasObstacle, add shortestPath test
change to use latest scala-maven-plugin with zinc
Merge pull request #39 from AI-comp/update_scala-maven-plugin

change to use latest scala-maven-plugin with zinc
Update README.md
Merge pull request #33 from AI-comp/shortestpath_obstacle

implement Tile.hasObstacle, add shortestPath test
Update .travis.yml

Deal with build fail problems.
issue #6: initial field generation
Merge branch '6_initializeField' of github.com:AI-comp/Terraforming into 6_initializeField

Conflicts:
	src/main/scala/net/aicomp/entity/Field.scala
	src/main/scala/net/aicomp/entity/Tile.scala