Thanks for the contribution though there are few things that I am not keen of.
I don't like adding a dependency library to the project just for one single line of code in this case formatting the date time. This library though really good is going to be a bit of a overkill just for the custom date time format support and it will increase the bundle size quite much. This is a relatively simple thing to do in the own codebase.
It is not probably the best way to replace one supported way of formatting the date with another. Better way would be to support both.
I have been thinking to add support for custom date formats but that hasn't had a high priority.
Support custom date-format like GitLen