Add cli commands to instrument an rcp service

the rcp service is the recommended way to copy files from a source repository to 'this' repository. the RCP sevice only has a http interface, which is a bit clumsy to use via command line if someone just wants to use it quickly.

suggest to add:

• vlt rcpsvc install Installs the service to the host
• vlt rcpsvc ls lists the current rcp tasks
• vlt rcpsvc add -f task.json Creates a new task
• vlt rcpsvc start <task-name> Starts a task
• vlt rcpsvc stop <task-name> Stops a task
• vlt rcpsvc rm <task-name> Removes a task
• vlt rcp <all rcp options> -t task.json <src> <dst> Creates a task.json with the specified options