[39] attempt to work around seemingly spurious warning about boost optional.

usign scoped ptr instead of boost optional.
[39] workaround for some g++: pass a concrete obj to avoid incorrect copy.

I encountered this with g++ 4.2.1 on FreeBSD 8.4 and confirmed this fix worked.
an easy fix, directly committing it myself.
[39] Revert "[39] workaround for some g++: pass a concrete obj to avoid incorrect copy."

reverting, committed to the wrong branch.
[39] Merge branch 'master' into issue39
[39] added comments about the usage
[39] editorial: fix a minor spacing issue.
Merge pull request #40 from bundy-dns/issue39

Issue39: work around g++ warning on the use of boost::optional