Add download attribute to download links

app/assets/javascripts/vue_pipelines_index/components/pipelines_artifacts.js

@@ -21,6 +21,7 @@ export default {
         <li v-for="artifact in artifacts">
           <a
             rel="nofollow"
+            download
             :href="artifact.path">
             <i class="fa fa-download" aria-hidden="true"></i>
             <span>Download {{artifact.name}} artifacts</span>

app/views/notify/project_was_exported_email.html.haml

@@ -2,7 +2,7 @@
   Project #{@project.name} was exported successfully.
 %p
   The project export can be downloaded from:
-  = link_to download_export_namespace_project_url(@project.namespace, @project) do
+  = link_to download_export_namespace_project_url(@project.namespace, @project), rel: 'nofollow', download: '', do
     = @project.name_with_namespace + " export"
 %p
   The download link will expire in 24 hours.

app/views/projects/artifacts/browse.html.haml

@@ -3,7 +3,7 @@
 .top-block.row-content-block.clearfix
   .pull-right
     = link_to download_namespace_project_build_artifacts_path(@project.namespace, @project, @build),
-      class: 'btn btn-default download' do
+      rel: 'nofollow', download: '', class: 'btn btn-default download' do
       = icon('download')
       Download artifacts archive

app/views/projects/builds/_sidebar.html.haml

@@ -33,7 +33,7 @@
               = link_to keep_namespace_project_build_artifacts_path(@project.namespace, @project, @build), class: 'btn btn-sm btn-default', method: :post do
                 Keep
-            = link_to download_namespace_project_build_artifacts_path(@project.namespace, @project, @build), class: 'btn btn-sm btn-default' do
+            = link_to download_namespace_project_build_artifacts_path(@project.namespace, @project, @build), rel: 'nofollow', download: '', class: 'btn btn-sm btn-default' do
               Download
             - if @build.artifacts_metadata?

app/views/projects/ci/builds/_build.html.haml

@@ -94,7 +94,7 @@
   %td
     .pull-right
       - if can?(current_user, :read_build, build) && build.artifacts?
-        = link_to download_namespace_project_build_artifacts_path(build.project.namespace, build.project, build), title: 'Download artifacts', class: 'btn btn-build' do
+        = link_to download_namespace_project_build_artifacts_path(build.project.namespace, build.project, build), rel: 'nofollow', download: '', title: 'Download artifacts', class: 'btn btn-build' do
           = icon('download')
       - if can?(current_user, :update_build, build)
         - if build.active?

app/views/projects/edit.html.haml

@@ -163,7 +163,7 @@
       - if @project.export_project_path
         = link_to 'Download export',  download_export_namespace_project_path(@project.namespace, @project),
-                method: :get, class: "btn btn-default"
+                rel: 'nofollow', download: '', method: :get, class: "btn btn-default"
         = link_to 'Generate new export',  generate_new_export_namespace_project_path(@project.namespace, @project),
                 method: :post, class: "btn btn-default"
       - else