Spiff up the upload_image() format handling

* attempt to detect format of *.img files automatically, recognizing:
  qcow2,raw,vdi,vmdk,vpc

Change-Id: I92ec141584ba8237b67ca640e401a1b88860747e
diff --git a/functions b/functions
index 664cfa0..0cfffb8 100644
--- a/functions
+++ b/functions
@@ -792,7 +792,12 @@
         *.img)
             IMAGE="$FILES/$IMAGE_FNAME";
             IMAGE_NAME=$(basename "$IMAGE" ".img")
-            DISK_FORMAT=raw
+            format=$(qemu-img info ${IMAGE} | awk '/^file format/ { print $3; exit }')
+            if [[ ",qcow2,raw,vdi,vmdk,vpc," =~ ",$format," ]]; then
+                DISK_FORMAT=$format
+            else
+                DISK_FORMAT=raw
+            fi
             CONTAINER_FORMAT=bare
             ;;
         *.img.gz)