Allow certian noderoles to move when a node changes deployments.

This update allows noderoles to move along with their node when moving a
node from one deployment to another, provided the following conditions
are met:

 * The noderole is PROPOSED
 * The noderole has never sucessfully run.
 * All of its children are in the same state

This allows users to edit the RAID configuration on a node before
committing it.