capture/use missing data sentinels

[dckc]

perhaps capture in XSD form?

how would we use this? omit i2b2 facts?

separating from #3

[dckc]

I just ran into:

Failed to execute: select * from tumor_item_value because: Data conversion error converting "XXXXX.9"

I used regexp_like as a work-around, but what we should do is use <td class='code-nbr'>XXXXX.9</td> fom naaccr-layout.

Also: test data with XXXX.9