Update Action.java

Add a bit more description to Action.PHYSICAL

I did actually find (I think) all the places in CraftBukkit where Action.PHYSICAL was used, so I decided to make this.
Merge #59

Thanks @Pocketkid2

commit 5620e70e1d9b532b4983dafb0c17f24d207a8aaa
Author: Adam
Date:   2013-12-10 09:00:40 -0800

Update Action.java

Add a bit more description to Action.PHYSICAL

I did actually find (I think) all the places in CraftBukkit where Action.PHYSICAL was used, so I decided to make this.