New: Allow 'mbid:' in search

Fixes #369

src/NzbDrone.Core/MetadataSource/SkyHook/SkyHookProxy.cs

@@ -138,7 +138,7 @@ namespace NzbDrone.Core.MetadataSource.SkyHook
             {
                 var lowerTitle = title.ToLowerInvariant();
 
-                if (lowerTitle.StartsWith("lidarr:") || lowerTitle.StartsWith("lidarrid:"))
+                if (lowerTitle.StartsWith("lidarr:") || lowerTitle.StartsWith("lidarrid:") || lowerTitle.StartsWith("mbid:"))
                 {
                     var slug = lowerTitle.Split(':')[1].Trim();
 
@@ -195,7 +195,7 @@ namespace NzbDrone.Core.MetadataSource.SkyHook
             {
                 var lowerTitle = title.ToLowerInvariant();
 
-                if (lowerTitle.StartsWith("lidarr:") || lowerTitle.StartsWith("lidarrid:"))
+                if (lowerTitle.StartsWith("lidarr:") || lowerTitle.StartsWith("lidarrid:") || lowerTitle.StartsWith("mbid:"))
                 {
                     var slug = lowerTitle.Split(':')[1].Trim();