Group jobs by project/pipeline

[cburgmer]

As teams will likely end up with multiple independent sets of jobs we should probably support some kind of separation of those sets. This could be a complex setup of multiple pipelines or many simple pipelines of microservices.

Color coding is one important visual aspect, as jobs of one group should by identifiable.

The "fail phases" graph follows a pipeline model, aggregating multiple pipelines in one overview will conflate what's happening below.

Ideas:

1. Provide namespaces when posting job/build information /builds/:ns/:job/:build
2. Trick D3 into providing similar colors for jobs of the same namespace

What we don't want:
buildviz does not want to hold information for multiple teams, rather it should be easy to deploy multiple instances of it.