rpc: add output indices to gettransactions

Someone apparently needs that to make a wallet but never asked.
If you read that and that's not what you wanted, the bugtracker
is at https://github.com/monero-project/monero/issues

src/rpc/core_rpc_server.cpp

@@ -388,6 +388,14 @@ namespace cryptonote
       res.txs_as_hex.push_back(e.as_hex);
       if (req.decode_as_json)
         res.txs_as_json.push_back(e.as_json);
+
+      // output indices too
+      bool r = m_core.get_tx_outputs_gindexs(tx_hash, e.output_indices);
+      if (!r)
+      {
+        res.status = "Failed";
+        return false;
+      }
     }
 
     BOOST_FOREACH(const auto& miss_tx, missed_txs)