Add .editorconfig
Add .editorconfig

EditorConfig is very well known config file for text editors/IDE's
with settings for project. This format supported by Vim, GNOME Builder,
Atom, Sublime and many others.

We will provide this configuration to be more friendly for newcomers.

Signed-off-by: Igor Gnatenko <71fb2d16c26f553767b965fdac40e83622cad277@redhat.com>

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