ds389log pmda: a new 389 Directory Server log processing PMDA

This provides client/server metrics from the 389 DS access log using
logconv.pl(1). Additional metrics provided by logconv.pl would be easy
to add if deemed useful, defining them in the %data hash should be enough
for most cases.

Running logconv.pl on an access log on a busy server without
defining the start/end time can be a long, CPU consuming
task. Thus, we always ask metrics for a certain time slice only
and calculate the actual metrics since the PMDA was started to
minimize resource usage and to avoid pmcd(1) dropping the PMDA (see
http://oss.sgi.com/bugzilla/show_bug.cgi?id=1036). In few cases the code
could perhaps a bit more Perlish but OTOH TIMTOWTDI.

For testing this locally we'll initially make use of the previously
captured access log included here, for basic sanity checking.
build, qa: bring the ds389log PMDA along to the party

Stitch pmdas/ds389log into the build, add test qa/960 which uses
the access log Marko provides in the absence of a pre-existing
log on the system.  Convert the perl pod that Marko already wrote
into a man page to make it available for online indexing.