Rename unspecified to make it clearer and in line with scrum terminology.

app/helpers/issues_helper.rb

@@ -15,7 +15,7 @@ module IssuesHelper
   # to allow filtering issues by an unassigned User or Milestone
   def unassigned_filter
     # Milestone uses :title, Issue uses :name
-    OpenStruct.new(id: 0, title: 'Unspecified', name: 'Unassigned')
+    OpenStruct.new(id: 0, title: 'None (backlog)', name: 'Unassigned')
   end
 
   def issues_filter

app/views/issues/_issues.html.haml

@@ -63,7 +63,7 @@
             - if @milestone.present?
               %strong= @milestone.title
             - elsif params[:milestone_id] == "0"
-              Unspecified
+              None (backlog)
             - else
               Any
             %b.caret
@@ -72,7 +72,7 @@
               = link_to project_issues_with_filter_path(@project, milestone_id: nil) do
                 Any
               = link_to project_issues_with_filter_path(@project, milestone_id: 0) do
-                Unspecified
+                None (backlog)
             - issues_active_milestones.each do |milestone|
               %li
                 = link_to project_issues_with_filter_path(@project, milestone_id: milestone.id) do