Fix crash when viewing or editing contacts without account

QuickContact and editor would crash when opening contacts with an
account_name and account_type from an invalid account or an account
without a contacts sync adapter.

Test: manually verify that a contact with a bogus account can be opened
in QuickContact and editor.

Bug 36782218

Change-Id: I943581be036dff07838ca630c0b771b370f9e2c7