Add TypeScript (support) and examples, module and API updates

[ndresx]

Changelog

• Update packages
• Add TypeScript (support)
• Add examples in /examples folder
• Add new props:
  • autoStart
  • zeroPadLength => zeroPadTime & zeroPadDays
  • onMount callback
  • onStart callback
  • onPause callback
• Refactor code/helpers
  • getTimeDifference => calcTimeDelta
  • Add new formatTimeDelta function
• Update docs to reflect latest changes

Enhancements

• Add zeroPadLength for days Add zeroPadLength for days #18 => zeroPadDays
• Add feature to pause countdown Add feature to pause the timer #14
• zeroPad can now zero pad numbers with any prefix improved zeroPad logic and added code for handling negative numbers #15
• Add simple API, available through getApi()
  • start()
  • pause()
  • isPaused()
  • isCompleted()

Bugfixes

• Fix issue with zeroPadLength and custom renderer when i use custom renderer, zeroPadLength not working #12

[coveralls]

Coverage remained the same at 100.0% when pulling 964bef4 on react-ts-examples-update into c8fdc9b on master.