The cloudscale_floating_ip module failed if no server was assigned to
the floating IP. This also adds a test to avoid a regression.
The only way to have a floating IP without a server assigned is to
delete the server where the floating IP is currently assigned. Under
normal circumstances it's not possible to have an unassigned floating
IP.
* Refactor cloudscale API code
Move code common to all cloudscale cloud modules into a common base
class.
This is needed as a prepartion of the cloudscale_floating_ip module.
* cloudscale_floating_ip module
New cloud module to manage floating IPs on the cloudscale.ch IaaS
service.