Enhancement package pkg openbsd

Better error handling for installing openbsd packages - if the output of `pkg_info` doesn't contain the expected output, we should exit 1. It is possible for ${status} to be populated with informational messages, e.g.: 

    The following new rcscripts were installed: /etc/rc.d/lighttpd
    See rc.d(8) for details.

causing cdist to cease reading the manifest any further.