Jira RUN-1106 Container handlers updates

Mostly audit and minor changes to nil from ""

Audit:
- GET /containers/json ListContainers
- POST /containers/create CreateContainer
- GET /containers/{id}/json GetContainer
- GET /containers/{id}/top TopContainer
- GET /containers/{id}/logs LogsFromContainer
- GET /containers/{id}/changes Changes
- GET /containers/{id}/export ExportContainer
- GET /containers/{id}/stats StatsContainer
- POST /containers/{id}/resize ResizeTTY
- POST /containers/{id}/start StartContainer
- POST /containers/{id}/stop StopContainer
- POST /containers/{id}/restart RestartContainer
- POST /containers/{id}/kill KillContainer
- POST /containers/{id}/update 404 not supported
- POST /containers/{id}/rename 404 not supported
- POST /containers/{id}/pause PauseContainer
- POST /containers/{id}/unpause UnpauseContainer
- POST /containers/{id}/attach AttachContainer
- GET /containers/{id}/attach/ws 404 not supported
- POST /containers/{id}/wait WaitContainer
- DELETE /containers/{id} RemoveContainer
- HEAD /containers/{id}/archive Archive
- GET /containers/{id}/archive Archive
- PUT /containers/{id}/archive Archive
- POST /containers/prune PruneContainers

Images etc PR's will follow.

Signed-off-by: Jhon Honce <jhonce@redhat.com>

pkg/api/handlers/compat/containers_pause.go

@@ -24,5 +24,5 @@ func PauseContainer(w http.ResponseWriter, r *http.Request) {
 		return
 	}
 	// Success
-	utils.WriteResponse(w, http.StatusNoContent, "")
+	utils.WriteResponse(w, http.StatusNoContent, nil)
 }