add run_as and created_by (to disambiguate user_name)
ensure defining a model sets run_as and created_by
switch genome model view to user created_by and run_as
switch genome model search result view to user created_by and run_as
both created_by and run_as are "affected_users"
switch build set XML view to use created_by and run_as
switch "fast" build XML view to use created_by and run_as
override created_by and run_as in 'export metadata' test
switch to created_by and run_by in GoldSnpComparison XML view
switch to created_by and run_as in model set XML view
switch to created_by and run_as in model Solr view
switch to created_by and run_as in population group XML view
switch to using created_by when updating project models
switch to created_by and run_as in TGI project XML view
assume default alignments care more about run_as than created_by
assume run_as is better replacement than created_by
assume run_as is a better replacement than created_by
begin migration of Model's user_name to created_by and run_as

CHANGELOG: Model now has created_by and run_as properties to distinguish the
different use cases user_name was being used for.  At this stage of the
migration user_name is still functional but it is now deprecated and may be
removed in the near future.  You should review any scripts you have that might
be getting Models with the user_name property and update them to use created_by
or run_as instead.