Embed Job to BuildResult type

[agis]

We already added the job params inside BuildResult{} so it might make sense to add the whole job.

[agis]

To do this, we have to:

1. extract any server-aware methods from Job into Server or something (to decouple Server from Job)
2. extract the job type to a package

We should also probably make NewBuildResult accept a job as a parameter, so that we don't have to do the construction in Work().