Improve bundles screen performance

[pierre]

Some Kill Bill deployments have very large catalogs (15GB+ XML). The following snippet can make the subscriptions screen unusable (while Kill Bill returns fast in about 2 minutes, the Rails app essentially hangs):

killbill-admin-ui/app/controllers/kaui/bundles_controller.rb

Lines 34 to 36 in ed56b30

	# TODO This doesn't take into account catalog versions
	catalogs = Kaui::Catalog.get_account_catalog_json(@account.account_id, nil, cached_options_for_klient) || []
	@catalog = catalogs[-1]

We need to rewrite the controller to avoid having to keep the whole catalog in memory to build the view.