Setting tag sfa-3.1-9

Setting tag sfa-3.1-9
Register can change the user keys using 'reg-keys' as well as 'keys'
also accept a single string rather than a list of keys
remove 'geni_api' from the registry GetVersion (which is not based on geni anymore)
bump the 'sfa' tag in the same registry GetVersion to 3
remove all mutable used as default arguments