RFC: Show  build status for packages which have travis integration

This PR displays the current build status for packages that have continuous integration running on Travis. 

While this is a minority of packages currently, it will hopefully cause some social pressure on packages to add tests and to run them automatically. 

See screenshot below on how it looks for packages with and without travis integration. 

![screen shot 2013-08-02 at 22 10 21](https://f.cloud.github.com/assets/378918/902972/334559c8-fba3-11e2-913c-f3a9b84d7656.png)