Fix up assets

This just fixes some problems that arose after mergings Tom's asset
changes into my code

Move images into assets so that image_tag works again
Add jquery back in

Add in jquery countdown css (Still broken. Fixing in later commit)

Fix zombietree json.
I had unjankified the zombietree_json previously but I only did it in
registration and not game so that broke stuff. Now its fixed

Move all :javascript into a content_for so that its properly loaded at
the end of the page as it should be

Still a few things that are broken. Will fix in later commit