implemented an optional per-service stderr log for capturing miscellaneous stderr...

implemented an optional per-service stderr log for capturing miscellaneous stderr output from services, similar to the old-style _unix.log files, since there are often useful warnings and error messages that never bubble up to syslog.  for clarity, the files now use _stderr as a suffix instead of _unix.  stderr logs are enabled by default.  included opensrf.xml example of how to disable it for a given service

git-svn-id: svn://svn.open-ils.org/OpenSRF/trunk@2035 9efc2488-bf62-4759-914b-345cdb29e865