Only one VM contextualisation file is being created for different resources using a same machine

[minondoa]

When creating the resources that will be tasked with creating VMs, if the different defined resources are going to use the same remote machine to create them, they all have to use the same "vm_user" and the same "private_key", since the will be using the same contextualisation file.

Have the DRM4G create a different contextualisation file for each resource, even if they're using the same remote machine to create the VMs.