Add static version of isSupported(), needsPermission(), requestPermission().
Make sure call back functions for Notify.requestPermission() are functions before trying to call them.
Remove instance version of isSupported(), needsPermission(), requestPermission().
Note: This is a breaking change!
Remove Notify.prototype.onPermissionGranted() and Notify.prototype.onPermissionDenied() since requestPermission() is now static.
Update README.md
Update tests.js with the new static functions.
Remove tests for PermissionGrantedCallback and PermissionDeniedCallback for now.
Merge pull request #9 from superkarn/staticFunctions

Static functions