added builds status png view (like travis png status) with SVG models

Just an status view that serves png images with information about builds (only build results not for individual steps) in three different sizes.

This looks just like:

![mamba_buildbot](https://f.cloud.github.com/assets/329766/417261/060a2b96-ac61-11e2-9ef4-a1afac5fd25a.png)

I've added the inkscape SVG models from where the PNG files are made.