Issue Search: Inconsistent time zone handling for creation dates

The date filter of the issue search is currently not always using the same time zone of the date histogram.

When filtering for a single day, for example, you usually get an empty bar to the left of the selected day in the date histogram.

NB: Stored issue creation date/time is the time at the server at issue creation. Issue creation date/time displayed in the issue block is adjusted for browser time zone. But the Creation Date facet uses the "raw" issue dates, and server timezone.