Jetpack: Bumping the version to 2.4b1 and tagging the beta.

New big features:
* Widget Visibility
* WordPress.com Connect
* Custom Post Types
* Some new shortcodes/widgets



git-svn-id: https://plugins.svn.wordpress.org/jetpack/trunk@756850 b8457f37-d9ea-0310-8a92-e5e31aec5664