Displayed `Last Modified` date

[bmll-chris]

The DUMMY_CREATED_DATE currently results in displaying 49 years as the last modified date for base directories in Jupyter, which is incorrect. Can this variable be changed to an empty string such that the displayed date is blank?

[ssanderson]

@bmll-chris I'm not sure offhand what the Jupyter frontend would do with an empty string in that case. My guess is that None (which would end up as null in javascript) is more likely to work, but that might still cause problems if the Jupyter javascript expects the modified date to always be populated.

[bmll-chris]

I have tested a null string and None - both work. Would you be able to implement one?