Shared folder asset handling

fixes #1659, fixes #1668

- removed relative asset url from css
- added asset helper to client
- updated references to shared assets
- added functional tests

ghost/admin/assets/sass/layouts/users.scss

@@ -209,7 +209,6 @@
             display: block;
             width: 110px;
             height: 110px;
-            background-image: url(/shared/img/user-image.png);
             background-size: cover;
             background-position: center center;
             border-radius: 100%;

ghost/admin/helpers/index.js

@@ -32,4 +32,22 @@
     Handlebars.registerHelper('url', function () {
         return Ghost.paths.subdir;
     });
+
+    Handlebars.registerHelper('asset', function (context, options) {
+        var output = '',
+            isAdmin = options && options.hash && options.hash.ghost;
+
+        output += Ghost.paths.subdir + '/';
+
+        if (!context.match(/^shared/)) {
+            if (isAdmin) {
+                output += 'ghost/';
+            } else {
+                output += 'assets/';
+            }
+        }
+
+        output += context;
+        return new Handlebars.SafeString(output);
+    });
 }());

ghost/admin/tpl/settings/user-profile.hbs

@@ -9,7 +9,8 @@
 <section class="content no-padding">
 
     <header class="user-profile-header">
-        <img id="user-cover" class="cover-image" src="{{#if cover}}{{cover}}{{else}}/shared/img/user-cover.png{{/if}}" title="{{name}}'s Cover Image"/>
+        <img id="user-cover" class="cover-image" src="{{#if cover}}{{cover}}{{else}}{{asset "shared/img/user-cover.png"}}{{/if}}" title="{{name}}'s Cover Image"/>
+
         <a class="edit-cover-image js-modal-cover button" href="#">Change Cover</a>
     </header>
 
@@ -18,7 +19,7 @@
         <fieldset class="user-details-top">
 
             <figure class="user-image">
-                <div id="user-image" class="img" {{#if image}}style="background-image: url({{image}});"{{/if}} href="#"><span class="hidden">{{name}}'s Picture</span></div>
+                <div id="user-image" class="img" style="background-image: url({{#if image}}{{image}}{{else}}{{asset "shared/img/user-image.png"}}{{/if}});" href="#"><span class="hidden">{{name}}'s Picture</span></div>
                 <a href="#" class="edit-user-image js-modal-image">Edit Picture</a>
             </figure>