Always return true if AppInitMain got to the end

This should fix a very rare travis failure in zapwallettxes, but
is also more correct, as you can currently race
ReacceptWalletTransactions with stop RPC calls to get bitcoind to
(IMO) eroneously return a non-0 exit code.

src/init.cpp

@@ -1726,5 +1726,5 @@ bool AppInitMain(boost::thread_group& threadGroup, CScheduler& scheduler)
     StartWallets(scheduler);
 #endif
 
-    return !fRequestShutdown;
+    return true;
 }