Merge pull request #39 from kyoushuu/master

Fix set_block for LoadMoreButton and make switching to songsview (rebased seif's patches)
fix selection bar
Fix back button for albums view
correctly exit after closing the window
toolbar: make pep8 happy
Merge pull request #38 from roignac/view_and_back_button

View fixes
Remove inactivity timeout
Don't call Gtk.main_quit() on window close
Separate callback for scrollbar visibility change and adjustment change

The two signals have different number of required parameters.