[adam-collard, r=gnuoy] This is a follow up branch to https://code.launchpad.net/~adam-collard/charms/trusty/swift-storage/add-pause-resume-actions/+merge/268233 to prevent config-changed from blindly (re)starting services when the unit is paused.
Normal flow is pause(), (optionally) change config -> changes should be persisted on disk, but nothing started. resume() -> services started.