scm: add "extra_info" column to repositories table and set serialize (#7146, #7047).

This column is for specific SCM.
Git 7 days problem (#7146) can not resolve unless storing branches info in database.

git-svn-id: svn+ssh://rubyforge.org/var/svn/redmine/trunk@5762 e93f8b46-1217-0410-a6f0-8f06a7374b81

db/migrate/20110511000000_add_repositories_extra_info.rb

@@ -0,0 +1,9 @@
+class AddRepositoriesExtraInfo < ActiveRecord::Migration
+  def self.up
+    add_column :repositories, :extra_info, :text
+  end
+
+  def self.down
+    remove_column :repositories, :extra_info
+  end
+end