Mock usage in RPG

The flow of creating RPM with usage of mock

(1) init mock in the background to download all repos from taget distro / arch after first GUI page

(2) init hawkey.Sack with cache dir inside mock build after mock download ends.

(3) before spec, rpm, srpm generation it should transfer all Files objects from spec.(Build)Requires to packages using hawkey.Selector(file=...) and hawkey.Goal.install()

(4) when mock build returns errors because of bash: <cmd>: command not found..., then append File("/usr/bin/<cmd>") into spec.BuildRequires and repeat step 3

The mock should be inited the way to persist all downloaded repos and packages downloaded in build root