Disable the progress bar if in quiet mode

Change-Id: I8fd3a8b6b38eba77b2b9fe3d397d8f8d79ac9b8e

anvil/downloader.py

@@ -159,7 +159,7 @@ class UrlLibDownloader(Downloader):
         try:
             with contextlib.closing(urllib2.urlopen(self._uri, timeout=self.timeout)) as conn:
                 c_len = conn.headers.get('content-length')
-                if c_len is not None:
+                if c_len is not None and not self.quiet:
                     try:
                         p_bar = self._make_bar(int(c_len))
                         p_bar.start()