Hide labels filter for MRs and remove unnecessary padding

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

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

@@ -2,7 +2,7 @@
   .check-all-holder
     = check_box_tag "check_all_issues", nil, false, class: "check_all_issues left"
   .issues-filters
-    .dropdown.inline.prepend-left-10
+    .dropdown.inline
       %a.dropdown-toggle.btn{href: '#', "data-toggle" => "dropdown"}
         %i.icon-user
         %span.light assignee:

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

 = render "head"
 .row
   .col-md-3
-    = render 'shared/project_filter', project_entities_path: project_issues_path(@project)
+    = render 'shared/project_filter', project_entities_path: project_issues_path(@project), labels: true
   .col-md-9.issues-holder
     = render "issues"

app/views/shared/_project_filter.html.haml

@@ -26,17 +26,18 @@
           = link_to project_filter_path(state: 'all') do
             All
 
-    %fieldset
-      %legend Labels
-      %ul.list-group
-        - issue_label_names.each do |label_name|
-          = link_to labels_filter_path(label_name), class: label_filter_class(label_name) do
-            %span{class: "label #{label_css_class(label_name)}"}
-              %i.icon-tag
-            = label_name
-            - if selected_label?(label_name)
-              .pull-right
-                %i.icon-remove
+    - if defined?(labels)
+      %fieldset
+        %legend Labels
+        %ul.list-group
+          - issue_label_names.each do |label_name|
+            = link_to labels_filter_path(label_name), class: label_filter_class(label_name) do
+              %span{class: "label #{label_css_class(label_name)}"}
+                %i.icon-tag
+              = label_name
+              - if selected_label?(label_name)
+                .pull-right
+                  %i.icon-remove
 
     %fieldset
       - if %w(state scope milestone_id assignee_id label_name).select { |k| params[k].present? }.any?