Prevent custom content being overwritten
Test custom content on sessionDataUpdated
Clear Session on authenticator restore, update tests

One duplicate test removed, test updated to retain existing content where applicable.
Test for when the authenticator triggers the sessionDataUpdated event expects data
to be overwritten
Revert clear session on sessionDataUpdated, update tests

Tests titles have been updated to reflect the data resolved from the authenticator
promises is merged in to the existing data.
Merge branch 'next' of https://github.com/peterchoo/ember-simple-auth into next