Issue with Unmarshaling Flavors #195

As detailed in hashicorp/terraform#10130, Gophercloud was triggering an unmarshal error when a flavor's RAM was too large to fit in an integer:

https://github.com/gophercloud/gophercloud/blob/master/openstack/compute/v2/flavors/results.go#L32

Should int be changed to int64? If so, might as well change Disk, Swap, and VCPUs.

While trying to resolve the above Terraform issue, I also came across MinDisk and MinRAM that should probably also be changed:

https://github.com/gophercloud/gophercloud/blob/master/openstack/compute/v2/images/results.go#L36-L37

Edit: probably also here: https://github.com/gophercloud/gophercloud/blob/master/openstack/imageservice/v2/images/results.go#L39-L43

Thoughts?