configurehood: Wait for the config AP to build when in sta mode

The configurehood script is started at the same time for all
routers. Thus, if one router sets up its configap, another may
just go into wXsta at the very same moment. This creates a race
condition between configap setup and wXsta download.

To circumvent this, we add a sleep to the wXsta routine, so the
wXsta always comes later, but is still run every 5 minutes.

Signed-off-by: Adrian Schmutzler <freifunk@adrianschmutzler.de>
Reviewed-by: Fabian Bläse <fabian@blaese.de>