AJCC N Descriptor Code Cleanup

ajcc7_n ajcc7_ndescriptor ajcc7_ndescriptor stor_ajcc7_ndescriptor Description
<Any value> ERROR <BLANK> <BLANK> If N Descriptor is an error, both should be set to blank
NA <Any value> <BLANK> N For N values of NA
<BLANK> <Any value> <BLANK> <BLANK> For missing N values caused by an ERROR in nodes
<Any value> <Any value> MATCH MATCH For all other cases, leave codes as they are