added Nancy pipelines for error handling,

cleaned up container registrations.

NzbDrone.Api/ErrorManagment/ErrorPipeline.cs

@@ -0,0 +1,28 @@
+using System;
+using System.Linq;
+using NLog;
+using Nancy;
+
+namespace NzbDrone.Api.ErrorManagment
+{
+    public class ErrorPipeline
+    {
+        private readonly Logger _logger;
+
+        public ErrorPipeline(Logger logger)
+        {
+            _logger = logger;
+        }
+
+        public Response HandleException(NancyContext context, Exception exception)
+        {
+            if (exception is ApiException)
+            {
+                _logger.WarnException("API Error", exception);
+                return ((ApiException)exception).ToErrorResponse();
+            }
+            _logger.ErrorException("Unexpected error", exception);
+            return null;
+        }
+    }
+}