add N/A to form fields

[andy-duncan]

several of the form fields need to be able to be marked as N/A

e.g. when certain lab results are not available for a patient, we need to let them continue

thinking that we can just indicate in the directive options, whether it should be provided as an option, and then just use a convention-based approach for naming the field.

i.e. patient.fieldValue --> patient.fieldValueNA

We will need to make validation account for this.

[andy-duncan]

made the whole page of vitals and results optional when you select a checkbox