Add spec url, demo url and tutorial url
add feature support in IE. Not supprted for any version of IE
add feature support in Firefox. Refer to browser compatility section here https://developer.mozilla.org/en-US/docs/WebAPI/Battery_Status
add feature support in rest of the browser. The feature is not supported in any other browser than Firefox
update percentage usage to 0.00 as I am not able to determine it at this time. Test passed
Add testing section to help contributors like me
Update testing section
Merge pull request #460 from jaydeepw/master

Add Battery-Status API feature data