func (i *Indexer) AddRaw(coll string, idx mgo.Index) {
	i.indexes = append(i.indexes, index{
		coll:  coll,
		index: idx,
	})
}
func (i *Indexer) AddRaw(coll string, idx mgo.Index) {
	i.indexes = append(i.indexes, index{
		coll:  coll,
		index: idx,
	})
}
// AddRaw will add a raw mgo.Index to the internal index list.