Add asset images for Htek brand and models (#348)

* Brand and model images for Provisioner/HTek

* ImageMagick scripts for brands an models

* Add HTek 902, 903, 912, 912G, UC924 & UC926

scripts/convert_brand_image.sh

@@ -0,0 +1,4 @@
+#!/usr/bin/env bash
+command -v convert >/dev/null 2>&1 || { echo >&2 "I require ImageMagick's 'convert' tool but it's not installed.  Aborting."; exit 1; }
+[ $# -lt 2 ] && { echo "Usage: ./convert_brand_image.sh <input_image> <output_image_base_name>"; exit 1; }
+convert "$1" -trim +repage -gravity center -resize 80x60 -background white -gravity center -extent 100x80 "$2".png

scripts/convert_model_image.sh

@@ -0,0 +1,7 @@
+#!/usr/bin/env bash
+command -v convert >/dev/null 2>&1 || { echo >&2 "I require ImageMagick's 'convert' tool but it's not installed.  Aborting."; exit 1; }
+[ $# -lt 1 ] && { echo "Usage: ./convert_model_image.sh <input_images>..."; exit 1; }
+for var in "$@"; do
+    filename="${var%%.*}"
+    convert "$var" -trim +repage -gravity center -resize 80x70 -background white -gravity center -extent 100x80 "$filename.jpg"
+done