Update create_snapshot to tag by default instead

Adding tags has been around for too long, I learned after I reviewed the history more. This change has been modified to add the parameter 'add_tag' which gives the calling code the ability to limit the function to doing actually what it says: creating snapshots (2.13.2 functionality), not creating them AND adding a tag (post 2.13.2 functionality). The default however is set to the functionality that has become standard over the last couple years.