Renaming the related collection of SequenceField on `collection_name` parameter change

[bdragon300]

It's needed to track SequenceField.collection_name parameter and rename the related collection if it has changed. Also keep in mind that the collection can be in different connection (SequenceField.db_alias). Also don't forget to check if collection with new name is already defined in Documents.

Maybe it's better to interactively ask user if do the following during executing makemigrations command.