Display "Edit" link on the product details page (public store) if a user has such permission

[mariannk]

When browsing products in public store, show link 'Edit Product', when user is administrator (or have sufficient rights). Great time-saver for minor changes in products

1. Add public bool CurrentUserHasEditPermission { get; set; } to \Models\Catalog\ProductDetailsModel.cs

2. To ProductController, PrepareProductDetailsModel add
   //does the current user have edit permission?
   model.CurrentUserHasEditPermission = _permissionService.Authorize(StandardPermissionProvider.AccessAdminPanel) &&
   _permissionService.Authorize(StandardPermissionProvider.ManageProducts);

3. To \Views\Product\ProductTemplate.Simple.cshtml and \Views\Product\ProductTemplate.Griouped.cshtml add something like the code below

                   @if (Model.CurrentUserHasEditPermission)
                   {
                       <div class="edit-product">
                           <a href="@Url.Action("Edit", "Product", new {id = Model.Id, area = "Admin"})">@T("Common.Edit")</a>
                       </div>
                   }
   

We just need to create better UI. Good idea - http://codepen.io/MeredithU/pen/jcsvx (but should we attach "font-awesome" just for one icon?

Please see http://www.nopcommerce.com/boards/t/41611/feature-request-front-end-edit-option-for-admins.aspx (put it to the top -"Administration" link)
P.S. Right now ignore for vendors