[BACK_INCOMPAT] Make `fabric.Object#toDataURL` synchronous. Fix `fabric.Object#cloneAsImage` to preserve angle. Closes #596
when use nodejs load remote image  with fullpath

sometime use server generate image, and passing parameter in url
so when send request should use full path, not only pathname
Merge pull request #605 from tka/patch-1

Load remote image with full path in node.js
Implement dashed stroke + some fixes with stroke, fill, removeShadow and clipTo + fixes in brushes
- fabric.Rect (now uses fabric.util.drawDashedLine), fabric.Line, fabric.Triangle, fabric.Polygon, fabric.Polyline, fabric.Image now supports dashed stroke
- fabric.Circle and fabric.Ellipse actual only supports native dashed stroke (browser must support context.setLineDash)
- fabric.Image.toSVG() has stroke/dashed-stroke support
- fabric.Object#clipTo has now affect on fabric.Image's stroke
- fabric.Shadow#affectStroke is considered - _removeShadow is now called in _renderFill (check whether stroke is to be affected) and _renderStroke
- reset shadow styles (contextTop) in fabric.PencilBrush, fabric.CircleBrush and fabric.Spraybrush (fabric.BaseBrush.removeShadowStyles)
Fix typo
Merge remote-tracking branch 'origins/master' into sketch
Merge remote-tracking branch 'mine/dashedStroke' into sketch
Build dist