Add the script to generate JSON input for imgsum -json-input

Signed-off-by: Igor Shishkin <me@teran.ru>

scripts/build-json-input.py

@@ -0,0 +1,19 @@
+#!/usr/bin/env python
+#
+# Usage:
+#   find <dir> -type f | build-json-input.py
+#
+# The script will return to STDOUT JSON document in a format for
+#   `imgsum -json-input`
+# Designed for testing purposes.
+#
+
+import json
+import sys
+
+if __name__ == '__main__':
+    files = []
+    for line in sys.stdin:
+        files.append(line.strip())
+
+    print json.dumps({'files': files}, indent=4)