In this issue we should add all the pending decisions about UI. Right now we have:

1. Use an icon to indicate the states of a message sent/received/being sent, ...
2. Use modal or view for forms like add a note? Currently using modal for add a note.
3. Book and IMSCP navigation by arrows (top, bottom, or both?)
4. Refresh complete site information, where? Courses view (pull to refresh), side menu (pull to refresh), settings (option)? Right now it's in settings.
5. When viewing notes, should we hide the contexts (Site, Course, Personal) that are empty? Right now we show them all and, if the user selects it, we tell him there are no notes.
6. Mod_book and mod_imscp behavior is weird if it fails to load, we should have the same behavior on both. Do we want to show arrows?
7. In most cases, if a pull to refresh fails we don't show error message, which makes me think the request was successful. Do we want to keep it like this?
8. Quiz: where to place navigation arrows and timer? MOBILE-1526----