MassGap classification -> HasMassGap

Current text has e.g. "classification of the GW signal, in order of descending probability, is BNS (78%), terrestrial (22%), BBH (<1%), NSBH (<1%), or MassGap (<1%)"

As @peter-shawhan noticed on DAC the text should have MassGap removed as a possible classification and instead added to the subsequent list of Has*** (EMBright) properties.