add https support options to metadata agent

This two new parameters for metadata agent:
* auth_insecure: turn off verification of the certificate for ssl, or
* auth_ca_cert: CA cert to check against with for ssl.
The two options where recently introduced with:
https://review.openstack.org/#/c/67181/

Change-Id: Ia05a1ec6b959f6b95e2e77350199bd6129c29271
Merge "add https support options to metadata agent"