Apply polish to specific nodes outside of the core ICDC model

[PhilipMusk]

With the data model explorer providing as much visibility into the ICDC data model as it will as of our next Production release, some effort should be devoted to applying the same level of polish to targeted nodes in the extended model as has been applied to properties in each of the core nodes.

In that they have received data courtesy of the COTC007B study, properties within the following nodes should now be fully defined:

1. visit
2. disease_extent
3. physical_exam
4. vital_signs
5. cycle
6. prior_surgery