Revert "Remove reflexive relationship user.posts (unused)"
Revert "Remove reflexive relationship user.posts (unused)"

This reverts commit f872fcf77fd699c0f7917ef71ebf63c4606fcfcd.

FirebaseExtended/emberfire,FirebaseExtended/emberfire,rtablada/emberfire,leifcr/emberfire,rtablada/emberfire,FirebaseExtended/emberfire,FirebaseExtended/emberfire,leifcr/emberfire