Fixed flash of "Save" button after save has completed

refs https://github.com/TryGhost/Team/issues/1597

- disabled automatic reset of the `<GhTaskButton>` used for saving so we don't have conflicting timeouts (button state auto reset is 2.5sec, display of save button before it's removed is 3sec)

ghost/admin/app/components/editor-labs/publish-management.hbs

@@ -20,6 +20,7 @@
             @successClass="midlightgrey"
             @failureClass="red"
             @showIcon={{false}}
+            @autoReset={{false}}
         />
     {{/if}}