[packagekit] InstallFile

[Richard Hughes]

I've added InstallFile for people to be able to click on a random .rpm
or .deb file and have PackageKit install the deps and do the install.
It's a different PolicyKit rule (one that _always_ prompts for a
password) as this is a different security context.

Could you backend guys add this if supported please - I know yum
supports this with localinstall.

Thanks.

Richard.