Might be used for monitoring validity in Zabbix later.

Force using a specified IPv[46] address passed as --resolve argument
to curl(1).
This function has been implemented via a shared include between scripts.

renamed:    hexaa-test.sh -> check_attributeauthority
renamed:    do-attributequery.sh -> query_saml2_attributes

This plugin
* attempts to download metadata,
* checks schema validity
* verifies signature
* checks if the validity of the metadata is far enough in the future

No longer rely on the defaults of do-attributequery.sh.