Added launcher with empty world and rosinstall file

As I tried to use the current Nao in Gazebo (and I finally couldn't) I'm adding:

1) A dummy launch file that launches empty world with the Nao robot. The current launch file tries to load a robocup football field which is not downloaded from the Gazebo models database:

    Error [ModelDatabase.cc:408] Unable to download model[model://robocup09_spl_field/materials/scripts/]
    Error [SystemPaths.cc:371] File or path does not exist[""]
    Error [RenderEngine.cc:409] URI doesn't exist[model://robocup09_spl_field/materials/scripts/]

2) A rosinstall file to get a workspace with everything for Nao as I found it right now. It also includes inside instructions on how to get it to work (until the point I got). Reproducing the instructions here:

    # To use this rosinstall
    # in your workspace src folder (let's say ~/nao_ws/src) do: 
    # wstool init .
    # wstool merge <this_file>
    # wstool up -j8
    # Then make sure you have all dependencies:
    # cd <your_workspace>
    # rosdep install --from-paths src --ignore-src --rosdistro hydro -y
    # Everything went fine? compile! 
    # catkin_make
    # Before launching you must install the meshes...
    # Go to nao_meshes_installer and execute the last version for your platform
    # In my case: ./naomeshes-0.6.7-linux-x64-installer.run
    # You'll get a window asking you stuff, like where to store it
    # You must store it in your workspace (so it extract directly inside of 
    # nao_meshes directory. So you'll get nao_meshes/mesh/V40 directory structure)

For the sake of completeness I'll explain where I got. I got the robot model to load in Gazebo, but there is some error with the hands (which I'll reproduce after this paragraph). Also no controllers could initialize.

	[ERROR] [1417694352.858359842]: This robot has a joint named "LHand" which is not in the gazebo model.
	[FATAL] [1417694352.858470531]: Could not initialize robot simulation interface
	[ERROR] [1417694352.860687169]: No joint named LHand. MimicJointPlugin could not be loaded.
	[ERROR] [1417694352.860785452]: No joint named LHand. MimicJointPlugin could not be loaded.
	[ERROR] [1417694352.860859614]: No joint named LHand. MimicJointPlugin could not be loaded.
	[ERROR] [1417694352.860933605]: No joint named LHand. MimicJointPlugin could not be loaded.
	[ERROR] [1417694352.861005688]: No joint named LHand. MimicJointPlugin could not be loaded.
	[ERROR] [1417694352.861077975]: No joint named LHand. MimicJointPlugin could not be loaded.
	[ERROR] [1417694352.861149026]: No joint named RHand. MimicJointPlugin could not be loaded.
	[ERROR] [1417694352.861219481]: No joint named RHand. MimicJointPlugin could not be loaded.
	[ERROR] [1417694352.861290216]: No joint named RHand. MimicJointPlugin could not be loaded.
	[ERROR] [1417694352.861358217]: No joint named RHand. MimicJointPlugin could not be loaded.
	[ERROR] [1417694352.861428645]: No joint named RHand. MimicJointPlugin could not be loaded.
	[ERROR] [1417694352.861496914]: No joint named RHand. MimicJointPlugin could not be loaded.
	[ERROR] [1417694352.861567763]: No joint named LHand. MimicJointPlugin could not be loaded.
	[ERROR] [1417694352.861640345]: No joint named LHand. MimicJointPlugin could not be loaded.
	[ERROR] [1417694352.861708811]: No joint named RHand. MimicJointPlugin could not be loaded.
	[ERROR] [1417694352.861780051]: No joint named RHand. MimicJointPlugin could not be loaded.
	[ WARN] [1417694352.863029445]: Link LFinger11 not found!
	[ WARN] [1417694352.863214805]: Link LFinger12 not found!
	[ WARN] [1417694352.863297080]: Link LFinger13 not found!
	[ WARN] [1417694352.863367741]: Link LFinger21 not found!
	[ WARN] [1417694352.863442127]: Link LFinger22 not found!
	[ WARN] [1417694352.863513551]: Link LFinger23 not found!
	[ WARN] [1417694352.863584133]: Link LThumb1 not found!
	[ WARN] [1417694352.863654355]: Link LThumb2 not found!
	[ WARN] [1417694352.863725743]: Link l_gripper not found!
	[ WARN] [1417694352.863792708]: Link RFinger11 not found!
	[ WARN] [1417694352.863863459]: Link RFinger12 not found!
	[ WARN] [1417694352.863931413]: Link RFinger13 not found!
	[ WARN] [1417694352.864002495]: Link RFinger21 not found!
	[ WARN] [1417694352.864073632]: Link RFinger22 not found!
	[ WARN] [1417694352.864144669]: Link RFinger23 not found!
	[ WARN] [1417694352.864218942]: Link RThumb1 not found!
	[ WARN] [1417694352.864290568]: Link RThumb2 not found!
	[ WARN] [1417694352.864361212]: Link r_gripper not found!

This maybe should go into the SIG google groups, thought of it after writing it, sorry!