change package name and sbt project name to rocket

rocket/src/main/scala/ptw.scala

@@ -1,4 +1,4 @@
-package Top {
+package rocket
 
 import Chisel._;
 import Node._;
@@ -213,5 +213,3 @@ class rocketPTW extends Component
     }
   }
 }
-
-}