Enhanced and simplified UI date and time handling
- Removed old date/time packages and cleaned up unused code.
- Now using moment.js for all times in the ui.
- Fixed all date displays to be in UTC (+00:00) timezone.
- Added back date and time filter functionality.
- Closes #103.
Merge pull request #137 from dsweet04/fix_ui_date_filters

Enhanced and simplified UI date and time handling