Initial implementation of an elasticsearch indexer in Go

Closes #1 (closed)

git/repo.go

@@ -103,17 +103,23 @@ func (r *Repo) EachFileChange(ins, mod, del FileFunc) error {
 		switch change.Action {
 		case difftree.Insert:
 			toF.Name = change.To.Name
-			return ins(toF)
+			err = ins(toF)
 		case difftree.Modify:
 			toF.Name = change.To.Name
-			return mod(toF)
+			err = mod(toF)
 		case difftree.Delete:
 			fromF.Name = change.From.Name
-			return del(fromF)
+			err = del(fromF)
+		default:
+			err = fmt.Errorf("Unrecognised change calculating diff: %+v", change)
+		}
+
+		if err != nil {
+			return err
 		}
 	}
-	return nil // TODO: should this be an "unrecognised action" error?
+	return nil
 }
 // EachCommit runs `f` for each commit within `fromSHA`...`toSHA` (i.e., the