Add --oslo option to init-repository

Oslo devs can use a local git mirror.

Change-Id: Id6f919ff65ddf0c0b5839316014f51d2293008fd
Reviewed-by: Sergio Ahumada <sergio.ahumada@digia.com>
Reviewed-by: Alex Blasche <alexander.blasche@digia.com>
Reviewed-by: Joerg Bornemann <joerg.bornemann@digia.com>