Install moveit_commander_cmdline.py into package specific directory, not to global bin.

[MoveIt! document](http://moveit.ros.org/wiki/MoveIt_Commander) expects `moveit_commander_cmdline.py` to be called via `rosrun`:

```
rosrun moveit_commander moveit_commander_cmdline.py
```

(There [was a question in answers](http://answers.ros.org/question/119151/cant-find-moveit-commander-exe-in-hydro/) that seems to have been deleted).

Indeed the python file is not placed in rosrun-able location.
```
$ find /opt/ros/hydro -iname moveit_commander_cmdline.py
/opt/ros/hydro/bin/moveit_commander_cmdline.py
```

Unless it's intended, installing scripts under each package folder is recommended in [catkin's doc](http://docs.ros.org/hydro/api/catkin/html/howto/installing_python.html), in addtion to the inconsistency with MoveIt! wiki I mentioned above.
```
ROS executables are installed in a per-package directory, not the distributions’s global bin/ directory. They are accessible to rosrun and roslaunch, without cluttering up the shell’s $PATH, and their names only need to be unique within each package. There are only a few core ROS commands like rosrun and roslaunch that install in the global bin/ directory.
```