Reorder initial operations to fix first run

The order in `initData` is a bit off, so I changed it:
   1. tagsController loads tags from redis to JS
   2. lessonController loads tags from videos.json into redis (but that's too late).

(I do not explain why this was not an issue on an ArchLinux machine but was an issue on an Ubuntu machine.)

Also, the docs say "init data by visiting ```localhost:22935/initData```" but init data is already called when launching `node --harmony app`. If calling `initData` when the server is already running is not useful, I can remove the documentation about it and remove the route.