More accurate SVG logo and rebulid 256&512px on it

Highly more accurate and nearly prefect SVG built using inkscape guideline. This screenshot is taken on inkscape:
![2013-07-17 20_49_54-app-icon svg - inkscape](https://f.cloud.github.com/assets/833473/813249/11b960a8-eefe-11e2-9700-73f8580a8cd6.png)