Integrate "Cluster upgrade" command in NuxeoCtl

When started on a node the `nuxeoCtl clusterUpdate` command should :

• fetch package definition from "Cluster Channel"
• run install / update
• restart if needed

the command should include 2 args :

 nuxeoCtl clusterUpdate <hotreload> <callback url>` 

hotreload

It may include 2 modes :

• install / update only packages that do not require restart
• install / update all packages that do not require restart

callback url

Allows to provide a callback url that nuxeoCtl should callback when update is complete.