Add relativeSize to Gruntfile.js
SVG: add class for hover elements

Element.isNode() throws exception when examing classless hover elemements
SVG: renderer does not create node labels for IE 9

IE 9 does not support innerHTML
SVG: outNode issue for Firefox

relatedTarget is the final target in mouseout event
originalTarget is the source target in mouseout event
https://developer.mozilla.org/en-US/docs/Web/API/event.relatedTarget
Merge pull request #453 from qinfchen/grunfile

Add relativeSize to Gruntfile.js
Merge pull request #455 from qinfchen/hoverClass

SVG: add class for hover elements
Merging PR#456
Merge pull request #457 from qinfchen/svg_onOut

SVG: outNode issue for Firefox