Fixes migrations that change string limits for sqlite.

git-svn-id: http://redmine.rubyforge.org/svn/trunk@1222 e93f8b46-1217-0410-a6f0-8f06a7374b81

db/migrate/060_change_changesets_committer_limit.rb

 class ChangeChangesetsCommitterLimit < ActiveRecord::Migration
   def self.up
-    change_column :changesets, :committer, :string
+    change_column :changesets, :committer, :string, :limit => nil
   end
 
   def self.down

db/migrate/070_change_attachments_content_type_limit.rb

 class ChangeAttachmentsContentTypeLimit < ActiveRecord::Migration
   def self.up
-    change_column :attachments, :content_type, :string
+    change_column :attachments, :content_type, :string, :limit => nil
   end
 
   def self.down

db/migrate/084_change_auth_sources_account_limit.rb

 class ChangeAuthSourcesAccountLimit < ActiveRecord::Migration
   def self.up
-    change_column :auth_sources, :account, :string
+    change_column :auth_sources, :account, :string, :limit => nil
   end
 
   def self.down