Generate hmac file with a newline at the end

This makes it slightly easier to cut&paste its content.

Signed-off-by: Guido Trotter <ultrotter@google.com>
Reviewed-by: Michael Hanselmann <hansmi@google.com>

lib/bootstrap.py

@@ -107,7 +107,7 @@ def GenerateHmacKey(file_name):
   @param file_name: Path to output file
 
   """
-  utils.WriteFile(file_name, data=utils.GenerateSecret(), mode=0400)
+  utils.WriteFile(file_name, data="%s\n" % utils.GenerateSecret(), mode=0400)
 
 
 def _InitGanetiServerSetup(master_name):