Add challenge module base class and PIN code challenge

Change-Id: I75c59bf1de921fad36563acdd37c1b4e80a29a3e
diff --git a/wscript b/wscript
index 2219b6e..2403d30 100644
--- a/wscript
+++ b/wscript
@@ -47,7 +47,7 @@
     conf.load('coverage')
 
     conf.load('sanitizers')
-    
+
     conf.write_config_header('src/ndncert-config.hpp')
 
 def build(bld):