Add reason enum to decision engine rejections

Co-authored-by: Mark McDowall <mark@mcdowall.ca>

src/NzbDrone.Core/DecisionEngine/Specifications/IDownloadDecisionEngineSpecification.cs

@@ -0,0 +1,14 @@
+using NzbDrone.Core.IndexerSearch.Definitions;
+using NzbDrone.Core.Parser.Model;
+
+namespace NzbDrone.Core.DecisionEngine.Specifications
+{
+    public interface IDownloadDecisionEngineSpecification
+    {
+        RejectionType Type { get; }
+
+        SpecificationPriority Priority { get; }
+
+        DownloadSpecDecision IsSatisfiedBy(RemoteMovie subject, SearchCriteriaBase searchCriteria);
+    }
+}