nitpicker: load initial config before announcement

This patch fixes a potential race condition that could happen if a
client connects to nitpicker before the signal for the import of the
initial configuration was delivered. In this case, nitpicker would be
unable to assign a domain to the session (because this information comes
from the configuration), rendering subsequent calls to 'mode' invalid.
The patch solves this problem by manually calling the signal handler
for importing the configuration.