Setting tag sfa-2.1-6

Setting tag sfa-2.1-6
native data model now has a authority x user (PI) relationship
no call to 'augment_records_with_testbed_info' for GetCredential
which means, registry can now be used without an underlying testbed
reviewed code about relationships b/w objects and related in pl driver
reviewed PL import wrt roles and pis
removed mentions to is_enabled in driver
small changes in update_relation* in driver interface
sfaadmin: can create authorities and attach pi users to them
sfaadmin: categories can be abbreviated
sfi list and sfaadmin list have a new -r/--recursive option
this means that List now supports an (optional) 'options' argument
sfi config can display config vars
sfaadmin code in sfa.client + /usr/bin/sfaadmin shortcut