Deprecate connection option

For #1392 

This adds accessors to handle deprecation of the `connection` option, which as discussed on the ticket is actually an instance of a subclass of `Fog::Service` not `Fog::Connection` as implied.

So now passing `service` upon creation is the expected means of declaring the parent/containing service. `connection` still works but warns.

Left the tests as is so we can see the deprecated behaviour still works.

Some models need to set up the service first so that they can refer there for additional data, a preliminary API call etc. These have been altered as well.

It then changes in small groups (per provider or provider/service) the calls. This change affects most models since they all piggy back on the service for requests.