Added SvgPathImage which renders whole QR code as one path

Rendering QR code as path removes white spaces which may occur when zooming the SVG image.

The image on the left side consists of one ``<path>`` element:
![svg_difference](https://f.cloud.github.com/assets/297993/993919/ae9af516-09a3-11e3-9b90-70d577a2c056.png)