Rename joy node

When remapping /joy, not only topic but also NODE is renamed.
This is because topic name and node name is the same.
```
<launch>
  <group>
    <remap from="/joy" to="/joy_org"/>
    <include file="$(pr2_bringup)/pr2.launch" />
  </group>
</launch>
```
However parameters are not remapped and don't work.