fix broken trailer in debian changelog

That extra space was making some of the more fragile parsing scripts
barf.
call ldconfig in debian postinst script

As required by Debian Policy Manual 8.1.1, see
http://www.debian.org/doc/debian-policy/ch-sharedlibs.html#s-ldconfig
don't install libhuboparams.la

Exclusing *.la-files from debian packages is an official policy as per
http://wiki.debian.org/ReleaseGoals/LAFileRemoval. They cause various
breakages; see
http://blog.flameeyes.eu/2008/04/what-about-those-la-files for an
explanation.