Branding: update Automating Attribute Release link

Update broken link from
http://support.aaf.edu.au/entries/321600-automating-attribute-release
to
http://support.aaf.edu.au/entries/22545567-Automating-Attribute-Release
Branding: IdP notification: update instructions

Update instructions regarding Automated Attribute Release in the IdP
activated notifications: refer to INTERNAL ID instead of UNIQUE URL
(which is now constructed on the DS according to the instructions on the
linked KB page).
Branding: moved AttributeFilter text into Branding

Moved text displayed on IdP detail -> SAML - Attribute Filter page
(views.fr.foundation.identityprovider.show.attributefilter.configurationurl)
from messages.properties into messages-branding.properties - as it
depends on AAF-specific process for publishing attribute filter.