Migration script for moving namespaces

[dnephin]

It would be a good idea to include a script to move the state of a job from one namespace to another.

[dnephin]

This is tangentially related to #221. In order for this script to work without requiring a restart of trond, trond will need to attempt to pull state data when a new job/service is added to the configuration.

This is also a good idea to support being able to remove a job from the config, and re-add it without losing it's run history. This can be done at the same time as making JobRun a top level entity in the state store.

[solarkennedy]

@chlgit did this with tronctl move.