Got the OSX autobuilder back running, and finally got a OSX build up for the 4.20130417 release. Also fixed the OSX app build machinery to handle rpath.

Made the assistant (and git annex sync) sync with git remotes that have annex-ignore set. So, annex-ignore is only used to prevent using the annex of a remote, not syncing with it. The benefit of this change is that it'll make the assistant sync the local git repository with a git remote that is on a server that does not have git-annex installed. It can even sync to github.

Worked around more breakage on misconfigured systems that don't have GECOS information.

... And other bug fixes and bug triage.