Update gravity dependency and add spec
Update gravity dependency and add spec

mzikherman/metaphysics-1,craigspaeth/metaphysics,craigspaeth/metaphysics,mzikherman/metaphysics-1,broskoski/metaphysics,artsy/metaphysics,mzikherman/metaphysics-1,artsy/metaphysics,mzikherman/metaphysics-1,artsy/metaphysics