Fix wrong canvas offset
- Copy inline style attributes from lowerCanvasEl to upperCanvasEl
- Copy classes from lowerCanvasEl to upperCanvasEl
- Add borderTopWidth, borderLeftWidth, paddingTopWidth and paddingLeftWidth (offsetAttributes) to canvas offset (fabric.util.getElementOffset) - these properties are not considered from getBoundingClientRect()
- JSfiddle's for tests - new: http://jsfiddle.net/Kienz/KRcsY/, old: http://jsfiddle.net/Kienz/xrMDr/
Reverse checks currentStyle & getComputedStyle => first check getComputedStyle and then currentStyle
Merge pull request #647 from Kienz/canvasOffset

Fix wrong canvas offset