#150 start caching plex media as well. refactored the availability checker. NEEDS TESTING. also, we need to make the Requests hit the plex api directly rather than hitting the cache as it does now.

PlexRequests.Services/Models/PlexAlbum.cs

@@ -0,0 +1,9 @@
+namespace PlexRequests.Services.Models
+{
+    public class PlexAlbum
+    {
+        public string Title { get; set; }
+        public string Artist { get; set; }
+        public string ReleaseYear { get; set; }
+    }
+}