fix: update playlist changes in local store

Move playlist change logic out of the library while we're at it and notify
the library of changes instead.

fixes #302

src/mpris.rs

@@ -1,5 +1,5 @@
-extern crate dbus_tree;
 extern crate dbus;
+extern crate dbus_tree;
 
 use std::collections::HashMap;
 use std::rc::Rc;
@@ -9,8 +9,8 @@ use std::time::Duration;
 use dbus::arg::{RefArg, Variant};
 use dbus::ffidisp::stdintf::org_freedesktop_dbus::PropertiesPropertiesChanged;
 use dbus::message::SignalArgs;
-use dbus_tree::{Access, Factory};
 use dbus::strings::Path;
+use dbus_tree::{Access, Factory};
 
 use crate::album::Album;
 use crate::episode::Episode;