[C++11] Follow the C++11 specification of operator new.

The signature changed in C++11 which we require now.
To get more details see the mailinglost in October 2012.

dune/common/debugallocator.hh

@@ -294,7 +294,7 @@ namespace Dune
 }
 
 #ifdef DEBUG_NEW_DELETE
-void * operator new(size_t size) throw(std::bad_alloc)
+void * operator new(size_t size)
 {
   // try to allocate size bytes
   void *p = Dune::DebugMemory::alloc_man.allocate<char>(size);