AssetsView input placeholder text from configuration

src/asset_manager/config/config.js

@@ -1,4 +1,4 @@
-module.exports =  {
+module.exports = {
   // Default assets
   // eg. [
   //  'https://...image1.png',
@@ -76,4 +76,7 @@ module.exports =  {
 
   // Default title for the asset manager modal
   modalTitle: 'Select Image',
+
+  //Default placeholder for input
+  inputPlaceholder: 'http://path/to/the/image.jpg'
 };

src/asset_manager/view/AssetsView.js

@@ -16,7 +16,7 @@ module.exports = Backbone.View.extend({
       <div class="${pfx}assets-header">
         <form class="${pfx}add-asset">
           <div class="${ppfx}field ${pfx}add-field">
-            <input placeholder="http://path/to/the/image.jpg"/>
+            <input placeholder="${view.config.inputPlaceholder}"/>
           </div>
           <button class="${ppfx}btn-prim">${view.config.addBtnText}</button>
           <div style="clear:both"></div>