marvin: factories for each api entity

factories will help define default test data for each entity. So a

Account.create(apiclient) returns a default account
VirtualMachine.deploy(apiclient) returns a virtualmachine etc

WIP: only skeletons, no flesh

Signed-off-by: Prasanna Santhanam <tsp@apache.org>
marvin factories: factory info required only for create-able entities

entities come in to life on 'create', 'deploy', 'associate', 'register'

Signed-off-by: Prasanna Santhanam <tsp@apache.org>