Fixed package name and project refactoring

As a standard, package names should be in all lowercase and it is recommended to use a reversed internet domain http://docs.oracle.com/javase/tutorial/java/package/namingpkgs.html. I suggest com.jadventure.game. I also tried to refactor the project folder structure to a more recognized one. I added .classpath and .project files for people using eclipse so that it is easier to open project. This will also help people importing the project to IntelliJ or Netbeans. I also added the json and junit dependencies into the project.