Add num_tenants, num_servers parameters to setup() function
Add loop to create servers and assign floating IPs to them
Correct handling of floating ips in fake cloudbackend
Fix handling of fake floating ip pools
Add args --num-tenants, --num-servers to setup and migrate parsers
Fix Server.add_floating_ip() function in fake cloud backend
Fix floating IP logic in setup() function
Update _info of the server after adding floating ip
Setup enhancements

Allow to set number of tenants and servers per tenant in 'setup' function.
Improve handling of Floating IPs in fake Cloud backend.
Add Floating IPs to the cloud upon setup.