Use same snippets icon everywhere. Fix list style for bordered-list

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

app/assets/stylesheets/base/mixins.scss

@@ -164,6 +164,7 @@
 @mixin basic-list {
   margin: 5px 0px;
   padding: 0px;
+  list-style: none;
 
   li {
     padding: 10px 0;

app/views/layouts/nav/_project.html.haml

@@ -100,7 +100,7 @@
   - if project_nav_tab? :snippets
     = nav_link(controller: :snippets) do
       = link_to namespace_project_snippets_path(@project.namespace, @project), title: 'Snippets', class: 'shortcuts-snippets', data: {placement: 'right'} do
-        = icon('file-text-o fw')
+        = icon('clipboard fw')
         %span
           Snippets