fix: Many un-returned promise (related to neumino#285)

Bluebird default behavior is to warn on un-returned promise. This PR
fix many of those in cursor.js

Author: nopnop

lib/cursor.js

@@ -114,7 +114,7 @@ Cursor.prototype._fetch = function() {
   var self = this;
   this._fetching = true;
 
-  var p = new Promise(function(resolve, reject) {
+  return new Promise(function(resolve, reject) {
     self.connection._continue(self.token, resolve, reject);
   }).then(function(response) {
     self._push(response);
@@ -124,6 +124,7 @@ Cursor.prototype._fetch = function() {
     self._canFetch = false;
     self._pushError(error);
   })
+
 }
 
 Cursor.prototype._push = function(data) {
@@ -142,7 +143,7 @@ Cursor.prototype._push = function(data) {
 // Try to solve as many pending promises as possible
 Cursor.prototype._flush = function() {
   while ((this._pendingPromises.length > 0) && ((this._data.length > 0) || ((this._fetching === false) && (this._canFetch === false)))) {
-    var fullfiller = this._pendingPromises.shift(); 
+    var fullfiller = this._pendingPromises.shift();
     var resolve = fullfiller.resolve;
     var reject = fullfiller.reject;
 
@@ -268,7 +269,7 @@ Cursor.prototype._each = function(callback, onFinish) {
   }
 
   self._next().then(resolve).error(function(error) {
-    // We can silence error when the cursor is closed as this 
+    // We can silence error when the cursor is closed as this
     if ((error.message !== 'You cannot retrieve data from a cursor that is closed.') &&
         (error.message.match(/You cannot call `next` on a closed/) === null)) {
       reject(error);
@@ -291,26 +292,26 @@ Cursor.prototype._eachAsyncInternal = function(callback, finalResolve, finalReje
 
   var nextCb = function() {
     self._stackSize++;
-    self._next().then(function(row) {
+    return self._next().then(function(row) {
       if (self._stackSize <= MAX_CALL_STACK) {
         if (callback.length <= 1) {
-          Promise.resolve(callback(row)).then(nextCb)
+          return Promise.resolve(callback(row)).then(nextCb)
         }
         else {
-          new Promise(function(resolve, reject) {
+          return new Promise(function(resolve, reject) {
             return callback(row, resolve)
           }).then(nextCb);
         }
       }
       else {
-        new Promise(function(resolve, reject) {
+        return new Promise(function(resolve, reject) {
           setTimeout(function() {
             self._stackSize = 0;
             if (callback.length <= 1) {
-              Promise.resolve(callback(row)).then(resolve).catch(reject);
+              return Promise.resolve(callback(row)).then(resolve).catch(reject);
             }
             else {
-              new Promise(function(resolve, reject) {
+              return new Promise(function(resolve, reject) {
                 return callback(row, resolve)
               }).then(resolve).catch(reject);
             }