Add instagram background implementation and generalize application for other identity providers

app/assets/javascripts/supplier/app/models/user.js.coffee

@@ -1,14 +1,13 @@
 attr = DS.attr
 App.User= DS.Model.extend
-  facebook_id: attr('string')
-  email: attr('string')
   name: attr('string')
+  uid: attr('string')
+  provider: attr('string')
+  avatar: attr('string')
   list: DS.belongsTo('list') # in ember scope not many to many (yet)
   join_requests: DS.hasMany('join_request')
-  facebook_image_tag: (->
-    facebook_id = @get('facebook_id')
-    return '' unless facebook_id
-    url = "http://graph.facebook.com/#{facebook_id}/picture?type=square"
+  avatar_tag: (->
+    return unless avatar = @get('avatar')
     name = @get('name')
-    new Handlebars.SafeString "<img src=\"#{url}\" alt=\"#{name}\" title=\"#{name}\" class=\"user-facebook-image\">"
-  ).property('facebook_id', 'name')
+    "<img src='#{avatar}' alt='#{name}' title='#{name}' class='user-avatar-image #{@get('provider')}'>".htmlSafe()
+  ).property('avatar', 'name')