Changed "const X ref"s to "X const ref"s

- Brought older code up to current convention (with the help of a Python script)

include/internal/catch_stream.hpp

@@ -57,7 +57,7 @@ namespace Catch {
 
     struct OutputDebugWriter {
     
-        void operator()( const std::string &str ) {
+        void operator()( std::string const&str ) {
             writeToDebugConsole( str );
         }
     };