Save meta title and meta desc on post save

Closes #4369
- Renamed `editor-route-base` -> `editor-base-route` to bring it in alignment with the view and controller mixins
- Consolidated editor route code into editor-base-route
- Removed `serialize` from EditorEditRoute, as it reimplemented the ember default
Merge pull request #4385 from novaugust/save-meta

Save meta title and meta desc on post save