Fix minor defect in TIU date parsing
Fix minor defect in TIU date parsing

Added a check for the case where the 'tiuDate' parameter is '-1' or NaN,
which, as it turns out, are both valid entries. Also updated the
documentation to reflect the valid parameter values.

vistadataproject/nonClinicalRPCs,vistadataproject/nonClinicalRPCs,vistadataproject/nonClinicalRPCs