Device, TestJob: better object representation
Device, TestJob: better object representation

This makes each object be presented with pretty much all information we
need while debugging scheduler problems in the console.

Change-Id: I17f3018215c392649d21fb866aecaf6ade9aae2c

Linaro/lava-server,OSSystems/lava-server,OSSystems/lava-server,Linaro/lava-server,OSSystems/lava-server,Linaro/lava-server,Linaro/lava-server