add image filters

README.md

@@ -31,6 +31,12 @@ Bing.images("Ninja Turtles", function(error, res, body){
   console.log(body);
 }, {skip: 50});
 ```
+Adding filter(s) for the Image Search
+```js
+Bing.images("Ninja Turtles", function(error, res, body){
+  console.log(body);
+}, {imagefilters: 'Size:Small+Color:Monochrome'});
+```
 
 ##### Specify Market
 Getting spanish results:

lib/bing.js

@@ -62,7 +62,8 @@ var Bing = function( options ) {
                    + qs.stringify({ "Query": "'" + query + "'" })
                    + "&$top=" + opts.top
                    + "&$skip=" + opts.skip
-                   + (opts.market ? "&Market=%27" + opts.market + "%27" : '');
+                   + (opts.market ? "&Market=%27" + opts.market + "%27" : '')
+                   + (opts.imagefilters ? "&ImageFilters=%27" + opts.imagefilters + "%27" : '');
 
     request({
       uri: reqUri,