ForeignAPIRepo: Fetch thumb error from foreign repo

When the api of the foreign repo gives a thumb error, this is now
reported to the user.

This can produce an extra request to the api, when the language of the
user does not match the content language of the client. In that case an
extra request is used to get a localized error message.

Change-Id: I6bda81899d0f11a0091b973ab49fd8e0f976ee09
Merge "ForeignAPIRepo: Fetch thumb error from foreign repo"