Completed the initial version of main.cpp and added a new build target for the ntorrent binary.

Change-Id: I1905f18ef73b8dabf16e8f85de1cc83220b6ad1c
diff --git a/wscript b/wscript
index fc24ded..a4c72b3 100644
--- a/wscript
+++ b/wscript
@@ -59,6 +59,12 @@
         includes='src',
         export_includes='src',
     )
+    # main
+    bld(
+      target='ntorrent',
+      features='cxx cxxprogram',
+      source='src/main.cpp',
+      use = 'BOOST nTorrent')
 
     if bld.env["WITH_TESTS"]:
         feature_list += ' cxxstlib'