Hide retry import form for non masters

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

app/views/projects/import.html.haml

@@ -15,6 +15,7 @@
       %h2
         Import failed. Retry?
   %hr
+  - if can?(current_user, :admin_project, @project)
     = form_for @project, url: retry_import_project_path(@project), method: :put, html: { class: 'form-horizontal' } do |f|
       .form-group.import-url-data
         = f.label :import_url, class: 'control-label' do