Show User Agent in System->Tasks for externally triggered commands (#63)

(cherry picked from commit fe8f319f7bfdadb7218b6313ada6cae1d2a35ad8)

Co-authored-by: Taloth Saldono <Taloth@users.noreply.github.com>

src/NzbDrone.Common/Http/UserAgentParser.cs

@@ -0,0 +1,21 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace NzbDrone.Common.Http
+{
+    public static class UserAgentParser
+    {
+        public static string SimplifyUserAgent(string userAgent)
+        {
+            if (userAgent == null || userAgent.StartsWith("Mozilla/5.0"))
+            {
+                return null;
+            }
+
+            return userAgent;
+        }
+    }
+}