build+src: Updating common.hpp to import (std|boost)::(shared_ptr|function|...) into ndn namespace

Also fixing a small bug in wscript.

Change-Id: I8f20caa177cc015b7433d1ecd3db385f533437c6
diff --git a/tests/wscript b/tests/wscript
index c63c031..7c55872 100644
--- a/tests/wscript
+++ b/tests/wscript
@@ -4,7 +4,7 @@
 
 def build(bld):
     unittests = bld.program (
-        target="unit-tests",
+        target="../unit-tests",
         features = "cxx cxxprogram",
         source = bld.path.ant_glob(['**/*.cpp']),
         use = 'ndn-cpp-dev',