asyncd: typo in pod
asyncd: try to reuse socket when asking node

We use one socket per process per run. So if --fork is
active, there will be no socket reuse.
asyncd: add the hostname in $0

This ease the fact when multiple async run on the same host
asyncd: fix timeout bug & adding some debug
SyncDictFile: flush the data before rename
asyncd: ignore current plugin if failing cnx to node

We should not die when failing to connect to a node. Just move forward to the
next plugin to fetch.
asyncd: fix dataloss bug when sleeping too little

When sleeping too little, the code just discards every plugin, and
reverts to sleep $timeout sec.

Note, it was hot-fixed by f47da1da171b60d06753321a6e60686948940869,
so this commit completes the latter for a much proper fix.

Thx to trippeh on IRC for showing me the bug *very* clearly.