Show error message to a user trying to associate via cafe if his institution is not registered

refs #1239
Merge remote-tracking branch 'origin/branch-v2-rnp-cafe-block-unregistered' into branch-v2

Conflicts:
	config/locales/en/_rnp_mconf.yml
	config/locales/pt-br/_rnp_mconf.yml
Block shib login before association if institution not found

Was blocking the login via shibboleth if the user's institution is not found
only after submitting the forms in the association page. Now it is blocked
before it, when the user first access /secure.

Complements 85f0b2485ee7d6

refs #1239