fix(datalayer): make datalayer usable outside request context

fix when using datalayer outside request context but within app one
Merge branch 'fix-datalayer-app-context' of github.com:superdesk/eve into superdesk-fix-datalayer-app-context
Data layer usable outside of request context.
Merge branch 'superdesk-fix-datalayer-app-context' into develop