Add option to ignoring ssl errors

[ryanmerolle]

This would be useful for when configuring devices that still only have self-signed certs. A crude workaround was documented on the fortinet developers network page.
https://fndn.fortinet.net/index.php?/forums/topic/1896-examples-of-ansible-28-and-new-fortinet-modules-fortiosapi-in-action/&do=findComment&comment=7294