Add insecure option for swift backup

Add insecure option for swift backup

When running backups with the swift backup driver and an
https url for the swift endpoint, the config option
backup_swift_ca_cert_file must point to a valid server side
cert.

For test purposes, it is useful to be able to ignore
cert errors while still making a SSL/TLS connection, the way
one can with https:// urls and the curl command and the
swift client itself.

This commit adds a boolean CONFIG option, 'backup_swift_auth_insecure',
whose default value is False, in which case there is no change from
current behavior.  If this option is set to True, however, cert validation
is skipped for SSL/TLS.

DocImpact

Change-Id: I1ca88d8e083d95c2bdb86ae79a4d66e04f521ddb