Code review comment for lp:~artem-anufrij/audience/library-view

Made some comments on the diff about code style, but also:

- The library shouldn't be loaded into memory unless the user requests it. This is currently causing a long startup time when you just click on a file to open ;)

Non-blockers, but would be nice on this MR:
- Load the library async: Even if we are not loading the library on startup, clicking on it would still take a bit of time where it would look like its' frozen. Loading it async should also fix that
- HD Thumbnails. Because high res is best res