Bug 956332 - Reorganize Login Manager tests and update interfaces. r=dolske

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rename : toolkit/components/passwordmgr/test/unit/test_storage_mozStorage_notify.js => toolkit/components/passwordmgr/test/unit/test_notifications.js
rename : toolkit/components/passwordmgr/test/unit/test_storage_mozStorage_migrate.js => toolkit/components/passwordmgr/test/unit/test_storage_mozStorage.js