Add click handling of cli options

Signed-off-by: Fabio Utzig <utzig@apache.org>
diff --git a/scripts/requirements.txt b/scripts/requirements.txt
index 1198d45..7bc8758 100644
--- a/scripts/requirements.txt
+++ b/scripts/requirements.txt
@@ -1,2 +1,3 @@
 cryptography
 intelhex
+click