Create Trimmer interface

provider.go

@@ -28,6 +28,14 @@ type ConfigProcessor interface {
 	ProcessConfig (config Meta) error
 }
 
+// Trimmer is an object that needs to be routinely "trimmed". This can be
+// garbage collecting, sanity checking, etc.
+type Trimmer interface {
+	// Trim trims the object. It must not block for any significant length
+	// of time. It should be called every minute or so.
+	Trim ()
+}
+
 // FuncProvider provides a template.FuncMap.
 type FuncProvider interface {
 	Provider