fix for call of overloaded make_optional is ambiguous error

fix boost -> std

Use git-archive-all for packagine

Merge pull request cpp-netlib#623 from deanberris/update-googletest

Update googletest dependency

Generate new documentation

Manually fix wrong version information.

Generate documentation for 0.11.2.

Bumping release number to 0.11.2-rc0

Allowed IPv6 connections by fixing the resolver

Merge pull request cpp-netlib#446 from lyytinen/0.11-devel-fix-for-419

Fix for issue cpp-netlib#419