Fix obs-cocoa CPU cores log output

According to http://www.intel.com/content/www/us/en/architecture-and-technology/64-ia-32-architectures-software-developer-vol-2a-manual.html
the cores_per_package and logical_per_package returns the maximum number
of (logical) cores addressable per package instead of the actual number
of (logical) cores
Log OS name and version on OSX