JAVA-467: removed call to _check() from within getServerAddress because this method should not block.

It is used for information purpose and docs states it is null until data has been returned.
One example is that it made cursor.toString() block on long queries.

Author: agirbal

src/main/com/mongodb/DBCursor.java

@@ -678,8 +678,6 @@ public DBCollection getCollection(){
      * @return
      */
     public ServerAddress getServerAddress() {
-        _check();
-
         if (_it != null && _it instanceof DBApiLayer.Result)
             return ((DBApiLayer.Result)_it).getServerAddress();