Set scheduling policy before dropping privileges
Set scheduling policy before dropping privileges

Previously if set to daemonize, set to run with realtime priority, and
set to drop privileges, umurmur would try to set the scheduling policy
after dropping privileges, which would fail as unprivileged processes
are not allowed to set a realtime scheduling policy as of Linux 2.6.12.

Fixes #94.

fmorgner/umurmur,fmorgner/umurmur