Remove old rake task

lib/tasks/gitlab/enable_namespaces.rake

-namespace :gitlab do
-  desc "GITLAB | Enable usernames and namespaces for user projects"
-  task enable_namespaces: :environment do
-    warn_user_is_not_gitlab
-
-    migrate_user_namespaces
-    migrate_groups
-    migrate_projects
-  end
-
-  def migrate_user_namespaces
-    puts "\nGenerate usernames for users without one: ".blue
-    User.find_each(batch_size: 500) do |user|
-      if user.namespace
-        print '-'.cyan
-        next
-      end
-
-      username = if user.username.present?
-                   # if user already has username filled
-                   user.username
-                 else
-                   build_username(user)
-                 end
-
-      begin
-        User.transaction do
-          user.update_attributes!(username: username)
-          print '.'.green
-        end
-      rescue
-        print 'F'.red
-      end
-    end
-    puts "\nDone"
-  end
-
-  def build_username(user)
-    username = nil
-
-    # generate username
-    username = user.email.match(/^[^@]*/)[0]
-    username.gsub!("+", ".")
-
-    # return username if no matches
-    return username unless User.find_by(username: username)
-
-    # look for same username
-    (1..10).each do |i|
-      suffixed_username = "#{username}#{i}"
-
-      return suffixed_username unless User.find_by(username: suffixed_username)
-    end
-  end
-
-  def migrate_groups
-    puts "\nCreate directories for groups: ".blue
-
-    Group.find_each(batch_size: 500) do |group|
-      begin
-        if group.dir_exists?
-          print '-'.cyan
-        else
-          if group.ensure_dir_exist
-            print '.'.green
-          else
-            print 'F'.red
-          end
-        end
-      rescue
-        print 'F'.red
-      end
-    end
-    puts "\nDone"
-  end
-
-  def migrate_projects
-    git_path = Gitlab.config.gitlab_shell.repos_path
-    puts "\nMove projects in groups into respective directories ... ".blue
-    Project.where('namespace_id IS NOT NULL').find_each(batch_size: 500) do |project|
-      next unless project.group
-
-      group = project.group
-
-      print "#{project.name_with_namespace.yellow} ... "
-
-      new_path = File.join(git_path, project.path_with_namespace + '.git')
-
-      if File.exists?(new_path)
-        puts "already at #{new_path}".green
-        next
-      end
-
-      old_path = File.join(git_path, project.path + '.git')
-
-      unless File.exists?(old_path)
-        puts "couldn't find it at #{old_path}".red
-        next
-      end
-
-      begin
-        project.transfer(group.path)
-        puts "moved to #{new_path}".green
-      rescue
-        puts "failed moving to #{new_path}".red
-      end
-    end
-
-    puts "\nDone"
-  end
-end