All: Update all UTC time references to local time

[DanieleSalatti]

In our code we always print the dates explicitly in US format with code like:

date.toLocaleDateString("en-US")

Most countries use wither dd/MM/YYYY or YYYY/MM/dd, removing "en-US" will make it print in the default format for whatever locale the browser language is.

[DanieleSalatti]

https://en.wikipedia.org/wiki/Date_format_by_country