Clean-up connector api and add javadoc
Clean-up cimi model package
Make MachineImage and MachineConfig mult-cloud resources

Multiple provider mappings can be maitained per resource.
Each provider mapping defines the provider-specific identifier of the resource
on a provider (and location).
Allow multiple MachineConfigs to have the same name
Remove obsolete code from Network manager

Networks are now imported from providers upon account creation
Clients are not allowed to create a public network
Fix package of SiroccoConfiguration entity
Set default disk format to empty string to keep CIMI happy
Provider account creation operation can now import images, configs and networks
Add getMachineConfigs and getMachineImages operations
Update connector test module taking into account the automatic import of resources upon account creation
Update required version of java to 1.7
Update amazon connector to comply with new connector api

A dummy public network is returned on a per-account basis
Implementation of getMachineConfigs that returns EC2 instance types
Preliminary implementation of getMachineImages
Update mock connector following extension of connector api

creation of  a mock machine config, a public network, a machine image
getters of machine configs and machine images
Expect provider account id as resource creation parameter instead of provider type
Clean-up classes: add minimal javadoc, remove obsolete interfaces/classes
Add machine configs and machine images getters, update retrieval of machine image id
Update retrieval of machine image id, add new machine configs and images getters