Use CScheduler for net's DumpAddresses

Instead of starting Yet Another Thread to dump addresses,
use CScheduler to do it.

src/init.cpp

@@ -1378,7 +1378,7 @@ bool AppInit2(boost::thread_group& threadGroup, CScheduler& scheduler)
     LogPrintf("mapAddressBook.size() = %u\n",  pwalletMain ? pwalletMain->mapAddressBook.size() : 0);
 #endif
 
-    StartNode(threadGroup);
+    StartNode(threadGroup, scheduler);
 
 #ifdef ENABLE_WALLET
     // Generate coins in the background