[RFE] Change time format / time zone in GUI

A customer has reported an error in the "Activity" and "Cluster utilization" panels of the overview screen where times can be displayed in either 12hr or 24hr clock format within the same frame. All time formats used within the GUI should be the same.

This customer has also requested the possibility to switch between the 12hr and 24hr clock through a setting, as well as a setting to use "cluster time" and/or have the timezone be configurable.