ar71xx: Add Gainstrong MiniBox v1.0 support to trunk

This patch supersedes the v1 from September 17th.

Bumping the patch version - the MiniBox profile showed up under M, but
since it's called 'Gainstrong MiniBox v1.0' now it looks out of place.
Renamed the profile to gs-minibox-v1.mk to fix that.

The following patch adds support for the Gainstrong MiniBox into trunk
(or 'Designated Driver' :D ).

Fixed items:

- Inverted LED polarity (OOLITE seems to suffer from the same problem).
- Changed uppercase MINIBOX_V1_ prefix as requested.
- Prefixes are now gs_minibox_ similar to gs_oolite_ (same vendor).
- Mention the vendor (Gainstrong) in code headers.

Compiles fine, has been confirmed working by owners on 15.05.

Question: I've seen some boards use tools/firmware-utils/src/mktplinkfw.c,
the MiniBox images build fine without, so I'm wondering: do I need to add
it in there as well? Any added benefit?

Thank you

Signed-off by: Stijn Segers <francesco.borromini@inventati.org>

SVN-Revision: 47234

target/linux/ar71xx/base-files/lib/upgrade/platform.sh

@@ -318,6 +318,7 @@ platform_check_image() {
 	el-mini | \
 	gl-inet | \
 	mc-mac1200r | \
+	minibox-v1 |\
 	onion-omega | \
 	oolite | \
 	smart-300 | \