Migration code for JobManageNetworking added, tests still missing.
Added tests for the migration of JobManageNetworking.
Merge branch 'master' of https://github.com/juju/juju into job-manage-networking-upgrade
Merge branch 'master' of https://github.com/juju/juju into job-manage-networking-upgrade
Moved upgrade into alpha3.
Merge branch 'master' of https://github.com/juju/juju into job-manage-networking-upgrade
Changes after review.
Fixed conflicts after introduction of DocID.
Merge pull request #956 from TheMue/job-manage-networking-upgrade

Upgrade for JobManageNetworking

MigrateJobManageNetworking adds the JobMachineNetworking to all existing machines according but

- machines in a MAAS environment,
- machines in a manual environment,
- bootstrap node (host machine) in a local environment, and
- manually provisioned machines.