basic oAuth login buttons
refined social icon treatments and created signin button cluster
ClientSide: renamed User model to UserIdentity
introduce User.activeIdentiy to adapt a user to their active identity
remove dup id attributes: _creator->_authors->authors _plusAuthors->plusAuthors
capture user's username
Surface user.activeIdentity as userIdentity adapter to Client
Auto create an Identity when making a User
renamed file
add some convenient tasks to test models and scratch test