The current package gnupg does not allow to receive keys due to
disable-exec, disable-hkp configuration.

The patch removes these switches. To avoid unduely increasing the package
size the helper executables are put into a new package gnupg-utils.

The version is bumped to 1.4.20 to avoid an error when receiving keys.

Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>

Signed-off-by: Nicolas Thill <nico@openwrt.org>

Signed-off-by: Ian Leonard <antonlacon@gmail.com>

- update to latest version (v1.4.18)
 - add license info
 - add myself as maintainer

Signed-off-by: Nicolas Thill <nico@openwrt.org>