models: Added Equals method to tag model.

models/tag.go

@@ -5,3 +5,8 @@ type Tag struct {
 	Kind TagKind `bson:"kind"`
 	Name string  `bson:"name"`
 }
+
+// Equal returns true if the tags match one another.
+func (tag *Tag) Equal(other Tag) bool {
+	return tag.Kind == other.Kind && tag.Name == other.Name
+}