[packagekit] Updated FreeBSD Ports backend

[Anders F Björklund]

The FreeBSD Ports backend for PackageKit ("ports") was updated,
so it can now install/remove/update packages too - unlike before.

There is still no matching PolicyKit (-One) or DeviceKit (-Power),
so it's mostly for development since it uses "dummy" frameworks.


The backend uses the regular "portupgrade" and "portaudit" tools,
to access the ports/packages and security/vulnerabilities info.

When installing something it will try the package first, and then
build a package from the port if one isn't available for fetching:

---> Using the port instead of a package
---> Building '#{portdir}'
===> Cleaning for #{pkgname}
===> Extracting for #{pkgname}
===> Patching for #{pkgname}
===> Configuring for #{pkgname}
===> Building for #{pkgname}
===> Installing for #{pkgname}
===> Building package for #{pkgname}
===> Cleaning for #{pkgname}

All this happens "behind the scenes", during the installation...
All default options are chosen, to avoid interaction with user.

Normally it would show a ncurses-based dialog(1) with options,
when doing "make config" for the port Makefile (Configuring for).

--anders