Hide new issue button if not authorized

app/views/projects/issues/show.html.haml

@@ -6,9 +6,10 @@
     = @issue.created_at.stamp("Aug 21, 2011")
 
   %span.pull-right
-    = link_to new_project_issue_path(@project), class: "btn grouped", title: "New Issue", id: "new_issue_link" do
-      %i.icon-plus
-      New Issue
+    - if can?(current_user, :write_issue, @project)
+      = link_to new_project_issue_path(@project), class: "btn grouped", title: "New Issue", id: "new_issue_link" do
+        %i.icon-plus
+        New Issue
     - if can?(current_user, :modify_issue, @issue)
       - if @issue.closed?
         = link_to 'Reopen', project_issue_path(@project, @issue, issue: {state_event: :reopen }, status_only: true), method: :put,  class: "btn grouped reopen_issue"