Fixed animation activity, image was referenced badly.

Fixed bug:
http://bugzilla.gnome.org/show_bug.cgi?id=607053
Activity: /expericence/electric

When I click one of the buttons at the left top corner,It reports:
Coundn't find or load the file
gartoon/electric/tool-select.png
This activity is incomlete.
Exit it and report
the problem to the authors.