Modification to UsageList so that liters and date are displayed in
different font sizes
Changes to UsageList
Working version of UsageList with display of liters and dates
Modifications to UsageList: added locale specific number formatting,
started to add local specific date formatting.
date format in UsageList is displayed depending on locale
Added context menu to UsageList to delete single entry; outsourced options
menu into new class OptionMenuActivity