canonical-certification server and other -cli commands crash due to use of job.name rather than job.id

[Daniel Manrique]

- Install a Trusty server system
- Add the ppa:checkbox-dev/ppa
- install checkbox-ng plainbox-provider-certification-server
- run canonical-certification-server
- select the server-cert whitelist

Expected result:
- List of tests to run

Actual result:

  File "/usr/lib/python3/dist-packages/checkbox_ng/commands/cli.py", line 146, in render
    line = prefix + self.depth * ' ' + ' ' + title
TypeError: Can't convert 'NoneType' object to str implicitly

This is because cli.py still has job.name instead of job.id in that line. Switching that to job.id makes it work (though it shows namespaced job names). It can also be job.partial_id, but job.name is just bad :)

$ grep -r 'job\.name' *
checkbox-ng/checkbox_ng/commands/cli.py: title = job.name # THIS IS THE ONE
plainbox/plainbox/impl/job.py: if deprecated and job.name is not None:
plainbox/plainbox/impl/test_job.py: self.assertIn('B', [job.name for job in node.jobs])
plainbox/plainbox/impl/test_job.py: self.assertIn('B', [job.name for job in node.jobs])

[Daniel Manrique (roadmr)]

Critical because cli commands outright don't work if this bug is present.