10 seconds is quite long for configuration messages, and way too much
currently since we only talk through the local networking interface.
Set the default timeout to 2 seconds, and provide APIs through which
the timeout may be changed at run-time (mainly useful for the shell).
Note: The timeout_set() API is normally assumed to be called just once
for an application, based on the expected size of the network (hops &
latency). Trying to change it e.g. in a multi-threaded environment for
every message may not yield the expected results.
Signed-off-by: Johan Hedberg <johan.hedberg@intel.com>