PyNDN: Small change and installing API

Refs #1010 (http://redmine.named-data.net/issues/1010)
diff --git a/wscript b/wscript
index b48adf7..c0dbf11 100644
--- a/wscript
+++ b/wscript
@@ -193,6 +193,10 @@
 
     bld.ns3_python_bindings()
 
+    bld (features = "pyext",
+         source = bld.path.ant_glob (["PyNDN/**/*.py"]),
+         install_from = "."
+         )
 
 @TaskGen.feature('ns3fullmoduleheaders')
 @TaskGen.after_method('process_rule')