Create app to log down nap/sleeping time and duration

• Export result as excel-like file (csv)
• Set password lock
• Set alarm
• Choose nap type: Short nap (< 45 mins) or Long nap (> 90 mins)
• Auto stop sleep time counting by screen unlock or Internet connection from off to on
• Auto start sleep time counting by screen lock or Internet connection from on to off
• Record sleep time
• Display sleep time in different types of graphs
• Local Storage
• Check storage limit before saving and give warning if almost exceeding the limit
• Have dashboard to show the statistic
• Check time with ntp server to avoid large error (beware with the timezone)