Update test cases with attribution information in the bundle.

The new `multiwiki.zip` bundle exposes some issues with our handling of
corrupt image files, so we've put that one in `multiwiki.zip.new` for now.
The rest of the bundles have been updated.

Change-Id: Idd4a67852bdcfd5c1aa40365b561ba4285cdd13e
Always use bidi, even if the wiki is "in theory" only LTR.

RTL content can be included even in LTR wikis.

Change-Id: I03bc2c9cbb38fb5f89a4678676609526d3c1a27e
Render attribution page

Change-Id: I4e6c3b6d92088fe1a600ddb35eed66abfa630327