Merge branch 'issue_25889' into 'master'

Revert MattermostNotificationService and SlackNotificationService to MattermostS…

Closes #25889

See merge request !8240

db/migrate/20161227192806_rename_slack_and_mattermost_notification_services.rb

+class RenameSlackAndMattermostNotificationServices < ActiveRecord::Migration
+  include Gitlab::Database::MigrationHelpers
+
+  DOWNTIME = false
+
+  def up
+    update_column_in_batches(:services, :type, 'SlackService') do |table, query|
+      query.where(table[:type].eq('SlackNotificationService'))
+    end
+
+    update_column_in_batches(:services, :type, 'MattermostService') do |table, query|
+      query.where(table[:type].eq('MattermostNotificationService'))
+    end
+  end
+
+  def down
+    update_column_in_batches(:services, :type, 'SlackNotificationService') do |table, query|
+      query.where(table[:type].eq('SlackService'))
+    end
+
+    update_column_in_batches(:services, :type, 'MattermostNotificationService') do |table, query|
+      query.where(table[:type].eq('MattermostService'))
+    end
+  end
+end

db/schema.rb

@@ -11,7 +11,7 @@
 #
 # It's strongly recommended that you check this file into your version control system.
 
-ActiveRecord::Schema.define(version: 20161221140236) do
+ActiveRecord::Schema.define(version: 20161227192806) do
 
   # These are extensions that must be enabled in order to support this database
   enable_extension "plpgsql"