Fog should consistently implement `ready?` on all model classes

[loewenstein]

trafficstars

Some model implementation have a ready? method to check if a resource is ready.

Compare the following two examples: https://github.com/fog/fog-openstack/blob/4217d76368aa0c570b268e96a3cf21f760ccc967/lib/fog/compute/openstack/models/image.rb#L40 https://github.com/fog/fog-openstack/blob/4217d76368aa0c570b268e96a3cf21f760ccc967/lib/fog/image/openstack/v2/models/image.rb

All model classes should implement ready?.

Resources should know which status value should be considered as ready. E.g. image uses status == ACTIVE (see above link) while volume uses status == "available" (see https://github.com/fog/fog-openstack/blob/4217d76368aa0c570b268e96a3cf21f760ccc967/lib/fog/compute/openstack/models/volume.rb#L47)

[seanhandley]

I agree 👍

If you can spare some time to raise a pull request for models you've seen that aren't doing this then that'd be awesome.