dnf-context: initialize repos after calling setup() from plugins
dnf-context: initialize repos after calling setup() from plugins

Signed-off-by: Igor Gnatenko <ignatenko@redhat.com>

Closes: #237
Approved by: cgwalters

hughsie/libhif,rpm-software-management/libdnf,edynox/libdnf,hughsie/libhif,hughsie/libhif,rpm-software-management/libhif,Conan-Kudo/libhif,hughsie/libhif,rpm-software-management/libdnf,rpm-software-management/libhif,edynox/libdnf,edynox/libdnf,rpm-software-management/libhif,rpm-software-management/libdnf,rpm-software-management/libdnf,edynox/libdnf,rpm-software-management/libhif,Conan-Kudo/libhif,Conan-Kudo/libhif,Conan-Kudo/libhif