Display attribution information in apps
Display attribution information in apps

This passes /com/endlessm/<resource>/credits.json to the "image-
attribution-file" parameter of EosApplication so that image credits are
displayed.

This also requires a commit in eos-pantheon-tools to add this file to
each knowledge app's GResource.

[endlessm/eos-sdk#2939]

endlessm/eos-knowledge-lib,endlessm/eos-knowledge-lib,endlessm/eos-knowledge-lib,endlessm/eos-knowledge-lib