Add Openstack SSL Support

Allow Openstack connections to be protected with SSL.

Additionally, remove some unused methods in `EmsOpenstack`.

WIP: Looking at how to add tests for this.

Rebased: included tests and fixed a problem with the raw_connect method.

Rebased for rubocop
This method appears to be stateless, so the only reason for it being an instance method seems to be to enable the re-use of the method name. However, given this method does more than it's class method namesake, re-using the name may be confusing. I'd recommend `raw_connect_check_ssl()` or something like that. You may also want to make it a class method, given it doesn't use any instance state.