Fixed example app not launching

When starting the `examples/kv/app_scatter.kv` with `kvrun.py` the app crashes:

    $ python kvrun.py app_scatter.kv 
    [INFO   ] Kivy v1.6.0
    [INFO   ] [Logger      ] Record log in /home/jonas/.kivy/logs/kivy_13-03-29_31.txt
    [INFO   ] [Factory     ] 137 symbols loaded
    [DEBUG  ] [Cache       ] register <kv.lang> with limit=None, timeout=Nones
    [DEBUG  ] [Cache       ] register <kv.image> with limit=None, timeout=60s
    [DEBUG  ] [Cache       ] register <kv.atlas> with limit=None, timeout=Nones
    [INFO   ] [Image       ] Providers: img_tex, img_dds, img_pygame, img_pil, img_gif 
    [DEBUG  ] [Cache       ] register <kv.texture> with limit=1000, timeout=60s
    [DEBUG  ] [Cache       ] register <kv.shader> with limit=1000, timeout=3600s
    [INFO   ] [Window      ] Provider: pygame
    [DEBUG  ] [Window      ] Display driver x11
    [DEBUG  ] [Window      ] Actual window size: 800x600
    [DEBUG  ] [Window      ] Actual color bits r8 g8 b8 a0
    [DEBUG  ] [Window      ] Actual depth bits: 24
    [DEBUG  ] [Window      ] Actual stencil bits: 8
    [DEBUG  ] [Window      ] Actual multisampling samples: 4
    [INFO   ] [GL          ] OpenGL version <3.0 Mesa 9.0.2>
    [INFO   ] [GL          ] OpenGL vendor <Intel Open Source Technology Center>
    [INFO   ] [GL          ] OpenGL renderer <Mesa DRI Intel(R) Ivybridge Mobile >
    [INFO   ] [GL          ] OpenGL parsed version: 3, 0
    [INFO   ] [GL          ] Shading version <1.30>
    [INFO   ] [GL          ] Texture max size <8192>
    [INFO   ] [GL          ] Texture max units <16>
    [DEBUG  ] [Shader      ] Fragment compiled successfully
    [DEBUG  ] [Shader      ] Vertex compiled successfully
    [DEBUG  ] [ImagePygame ] Load </usr/lib/pymodules/python2.7/kivy/data/glsl/default.png>
    [INFO   ] [Window      ] virtual keyboard not allowed, single mode, not docked
    [DEBUG  ] [App         ] Loading kv <./kv.kv>
    [DEBUG  ] [App         ] kv <./kv.kv> not found
     Traceback (most recent call last):
       File "kvrun.py", line 34, in <module>
         KvApp(filename=sys.argv[1]).run()
       File "/usr/lib/pymodules/python2.7/kivy/app.py", line 527, in run
         root = self.build()
       File "kvrun.py", line 24, in build
         return Builder.load_file(self.options['filename'])
       File "/usr/lib/pymodules/python2.7/kivy/lang.py", line 1152, in load_file
         return self.load_string(data, **kwargs)
       File "/usr/lib/pymodules/python2.7/kivy/lang.py", line 1186, in load_string
         parser = Parser(content=string, filename=fn)
       File "/usr/lib/pymodules/python2.7/kivy/lang.py", line 785, in __init__
         self.parse(content)
       File "/usr/lib/pymodules/python2.7/kivy/lang.py", line 858, in parse
         objects, remaining_lines = self.parse_level(0, lines)
       File "/usr/lib/pymodules/python2.7/kivy/lang.py", line 947, in parse_level
         _objects, _lines = self.parse_level(level + 1, lines[i:])
       File "/usr/lib/pymodules/python2.7/kivy/lang.py", line 925, in parse_level
         'Invalid data after declaration')
     kivy.lang.ParserException: Parser: File "app_scatter.kv", line 3:
     ...
           1:Widget:
           2:    Scatter:
     >>    3:    size: image.texture_size
           4:    Image:
           5:        id: image
     ...
     Invalid data after declaration

I fixed it. See the pull-request.

-- Jonas