Instead of returning the cached image in collection, get (or find_by_id) method
should refresh the image data. This will fix the reload method, as actually it
doesn't really reload the image details.
The 'connection' accessor in collections and models actually refered to
a subclassed instance of Fog::Service which creates confusion in the
code.
References to 'connection' could have meant the service or the
Fog::Connection held within that service.
This deprecates the connection accessor and replaces it with `#service`
as a read only value. When a collection or model is initalised then
service should be passed.
This commit also updates all the changes to @connection made by
providers in model initialisers since these depending on the presence of
the 'connection' key. The key is still accepted by outputs a warning.
