Keep old path: db/database.sql.gz

Documentation elsewhere refers to this internal path, let's keep
it.

lib/backup/database.rb

@@ -6,10 +6,11 @@ module Backup
 
     def initialize
       @config = YAML.load_file(File.join(Rails.root,'config','database.yml'))[Rails.env]
-      @db_file_name = File.join(Gitlab.config.backup.path, 'database.sql.gz')
+      @db_file_name = File.join(Gitlab.config.backup.path, 'db', 'database.sql.gz')
     end
 
     def dump
+      FileUtils.mkdir_p(File.dirname(db_file_name))
       FileUtils.rm_f(db_file_name)
       compress_rd, compress_wr = IO.pipe
       compress_pid = spawn(*%W(gzip -1 -c), in: compress_rd, out: [db_file_name, 'w', 0600])

lib/backup/manager.rb

@@ -150,11 +150,11 @@ module Backup
     private
 
     def backup_contents
-      folders_to_backup + ["database.sql.gz", "uploads.tar.gz", "builds.tar.gz", "backup_information.yml"]
+      folders_to_backup + ["uploads.tar.gz", "builds.tar.gz", "backup_information.yml"]
     end
 
     def folders_to_backup
-      folders = %w{repositories}
+      folders = %w{repositories db}
 
       if ENV["SKIP"]
         return folders.reject{ |folder| ENV["SKIP"].include?(folder) }