Merge pull request #14 from yuhua-chen/michael

Fix coding style and update README
Change eventlistener click to mousedown.
Merge pull request #15 from yuhua-chen/will

Change eventlistener click to mousedown.
Merge pull request #16 from yuhua-chen/development

Improve the animation.
Fix ripple position bug and css3 animation for mobile device.
Improve css3 coding style.
Merge pull request #17 from yuhua-chen/will

Fix ripple position bug and css3 animation for mobile device.
Merge pull request #18 from yuhua-chen/development

Fix the wrong position of ripple on mobile device.
Remove unnecessary `preventDefault()` which caused failure trigger event on iOS.