add express endpoint for sending tx

lib/expressapp.js

@@ -369,6 +369,17 @@ ExpressApp.prototype.start = function(opts, cb) {
     });
   });
 
+  router.post('/v1/txproposals/:id/send/', function(req, res) {
+    getServerWithAuth(req, res, function(server) {
+      req.body.txProposalId = req.params['id'];
+      server.sendTx(req.body, function(err, txp) {
+        if (err) return returnError(err, res, req);
+        res.json(txp);
+        res.end();
+      });
+    });
+  });
+
   // TODO Check HTTP verb and URL name
   router.post('/v1/txproposals/:id/broadcast/', function(req, res) {
     getServerWithAuth(req, res, function(server) {