Fix wrong shebang in download scripts

Download does not support python2 so shebang
could cause problem.
This commit fixes that or removes shebang where
not necessary.

Issue-ID: OOM-1964

Change-Id: I443f5ef61b9bddfddba66d858d8f65c5ceacd90a
Signed-off-by: Milan Verespej <m.verespej@partner.samsung.com>
diff --git a/build/download/npm_downloader.py b/build/download/npm_downloader.py
index 369af72..ed4152b 100755
--- a/build/download/npm_downloader.py
+++ b/build/download/npm_downloader.py
@@ -1,4 +1,4 @@
-#! /usr/bin/env python
+#! /usr/bin/env python3
 # -*- coding: utf-8 -*-
 
 #   COPYRIGHT NOTICE STARTS HERE