fix a lock indentation in main.cpp

- also ensure alphabetical ordering in file header

src/main.cpp

@@ -26,8 +26,8 @@
 #include <boost/filesystem/fstream.hpp>
 #include <boost/thread.hpp>
 
-using namespace std;
 using namespace boost;
+using namespace std;
 
 #if defined(NDEBUG)
 # error "Bitcoin cannot be compiled without assertions."