Merge pull request #1 from zhaozheid/master

update
change the inner class name in PlayingScene
Merge branch 'zz_local'
Merge pull request #2 from zhaozheid/master

update
Merge pull request #39 from joeyzhang1989/master

change the inner class name in the PlayingScene class
solve javadoc conflict
Merge pull request #40 from joeyzhang1989/master

solve javadoc conflict
Merge branch 'zz_local'
Road & Tower now Observable

Road & Tower now Observable
Merge branch 'master' into zz_local