MINOR: peers: adds counters on show peers about tasks calls.

MINOR: peers: adds counters on show peers about tasks calls.

This patch adds a counter of calls on the orchestator peers task
and a counter on the tasks linked to applet i/o handler for
each peer.

Those two counters are useful to detect if a peer sync is active
or frozen.

This patch is related to the commit:
  "MINOR: peers: Add a new command to the CLI for peers."
and should be backported with it.