Angular upgrade v1.2.13

@gergely-ujvari I rebased your angular branch, updated to v1.2.13, squashed out the intermediate angular version updates, and fixed the authentication directive.

Do a sanity check, please.

@dwhly maybe take a spin through https://angular-upgrade-1.dokku.hypothes.is/ if you get a chance. It's building now and should be ready in a few minutes.

Fingers crossed for no regressions.