Add possibility to use child model-descriptions with properties containing a namespace

Add possibility to use child model-descriptions with properties containing a namespace relative to the global `__namespace`.

*Example:*

Origin

		{
          session: {
            state: "Active",
            detail: {
              actions: [
                {id: 1, name: "login"},
                {id: 2, name: "update"}
              ]
            }
          }
        }

Model description

        {
          __namespace: 'session',
          state: 'state',
          actions: 'detail.actions',
          __children: {
            actions: {
              id: 'id',
              action: 'name'
            }
          }
        }


Result

        {
          state: "Active",
          actions: [
            {id: 1, action: "login"},
            {id: 2, action: "update"}
          ]
        }