Revert "added ArticleProvenance model"
Revert "added ArticleProvenance model"

This reverts commit 1b076d3829dbde91e6eb99ed334ca8ef94a26016.

tschmorleiz/amcat,tschmorleiz/amcat,tschmorleiz/amcat,amcat/amcat,amcat/amcat,amcat/amcat,amcat/amcat,tschmorleiz/amcat,tschmorleiz/amcat,amcat/amcat,amcat/amcat