add show, logs and history commands

Do not yet merge, specs missing, plus show command can be improved (ie display matrix of builds, config for jobs).

![Screen Shot 2013-01-19 at 2 29 18 PM](https://f.cloud.github.com/assets/30442/80273/3d64d20e-623c-11e2-9a3d-f6bcc08d31f1.png)