Update explore sidebar

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

@@ -2,20 +2,20 @@
   = nav_link(path: ['dashboard#show', 'root#show', 'projects#trending', 'projects#starred', 'projects#index'], html_options: {class: 'home'}) do
     = link_to explore_root_path, title: 'Projects' do
       = icon('bookmark fw')
-      %span
+      .nav-link-text
         Projects
   = nav_link(controller: [:groups, 'groups/milestones', 'groups/group_members']) do
     = link_to explore_groups_path, title: 'Groups' do
       = icon('group fw')
-      %span
+      .nav-link-text
         Groups
   = nav_link(controller: :snippets) do
     = link_to explore_snippets_path, title: 'Snippets' do
       = icon('clipboard fw')
-      %span
+      .nav-link-text
         Snippets
   = nav_link(controller: :help) do
     = link_to help_path, title: 'Help' do
       = icon('question-circle fw')
-      %span
+      .nav-link-text
         Help