Link directly to the projects page instead of the root controller

If "Your Projects' Activity" dashboard setting were selected, it would be impossible to navigate to the projects page since the redirection would always bounce back to the activity dashboard.

Fixes bug introduced by !1446.

Author: stanhu

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

@@ -1,6 +1,6 @@
 %ul.nav.nav-sidebar
   = nav_link(path: ['root#index', 'projects#trending', 'projects#starred', 'dashboard/projects#index'], html_options: {class: 'home'}) do
-    = link_to root_path, title: 'Projects', data: {placement: 'right'} do
+    = link_to dashboard_projects_path, title: 'Projects', data: {placement: 'right'} do
       = icon('home fw')
       %span
         Projects