Some GSettings aren't saved until a clean exit

Not sure if this is app-specific, or a Granite issue. Some GSettings are not saved until you cleanly exit the app. This means if the app crashes, my computer dies, etc., I still lose some of the state.

For example, In Files if I show hidden files, the GSetting `org.pantheon.files.preferences show-hiddenfiles` instantly changes `true`. However, if I open a new tab, resize the window, change tab focus, or resize the sidebar, the relevant GSettings do not update until I close the app.

Instead, the app should save all of its GSettings right when they change (or very soon after).