Update istanbul
ignore canvas/jsdom/xmldom when browserifying
Merge pull request #1397 from tmpvar/browserify-support

Allow browserify to run over fabric.js
Update path.class.js

apply opacity property on paths.
Update polygon.class.js

Apply opacity property to poligon class.
Update ellipse.class.js

Always transparency rendering related.
Merge pull request #1405 from asturur/master

Managing opacity properties on polygon and path object