TOSCA Namespaces Support

TOSCA Simple Profiles allows template authors to declare their own types and templates and assign them simple names with no apparent namespaces. This is going to be discussed more in the TOSCA TC to create rules are needed to avoid collisions and apply their own namespaces when import and nesting occur. With the current heat-translator implementation it is expected that things like node type names are unique as well other things like requirements and capabilities. They are always unique for the TOSCA normative or base type but for custom it's not true. Consider the following scenario where two custom types definitions are imported in a single template,

node_types:
  tosca.nodes.Database.MongoDB
    derived_from: tosca.nodes.Database
      properties:
        name: { get_input: db_name }
        user: { get_input: db_user }
        password: { get_input: db_pwd }
    #interfaces:
node_types:
  tosca.nodes.Database.MongoDB
    derived_from: tosca.nodes.Database
  #interfaces:

where a custom type for MongoDB has created with certain expected properties and other things and other custom type uses default properties of MongoDB. Since they are of same node type, this will lead to a collision.