consistency fixes

app/views/projects/tags/_tag.html.haml

@@ -18,7 +18,7 @@
         = render 'projects/branches/commit', commit: commit, project: @project
     - else
       %p
-        = s_('TagsPage|Cannot find HEAD commit for this tag')
+        = s_("TagsPage|Can't find HEAD commit for this tag")
     - if release && release.description.present?
       .description.prepend-top-default
         .wiki

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

 - @no_container = true
 - @sort ||= sort_value_recently_updated
-- page_title _('Tags')
+- page_title _('TagsPage|Tags')
 - add_to_breadcrumbs("Repository", project_tree_path(@project))
 
 .flex-list{ class: container_class }

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

@@ -16,7 +16,7 @@
       - if @commit
         = render 'projects/branches/commit', commit: @commit, project: @project
       - else
-        = s_('TagsPage|Cannot find HEAD commit for this tag')
+        = s_("TagsPage|Can't find HEAD commit for this tag")
 
     .nav-controls.controls-flex
       - if can?(current_user, :push_code, @project)