failing: added asset test for libre office doc
mime types should be compatible with themselves
enable odt thumbnails of word documents

They might be handy anyway but in particular we still have some of these on the live servers and the assets can't be removed if the thumbdef is not around because proxy? will err out.

see https://labs.riseup.net/code/issues/4336
stub RemoteJob.site so all conversion is run in line.