Remove unused date_time_input and DateTimeInput
Remove unused date_time_input and DateTimeInput

These were left over from an earlier, failed attempt at adding event
time entry and are no longer needed.

dburr/SchoolIdolAPI,dburr/SchoolIdolAPI,SchoolIdolTomodachi/SchoolIdolAPI,dburr/SchoolIdolAPI,rdsathene/SchoolIdolAPI,rdsathene/SchoolIdolAPI,rdsathene/SchoolIdolAPI,SchoolIdolTomodachi/SchoolIdolAPI,SchoolIdolTomodachi/SchoolIdolAPI