Jetpack: Contact Form: Patching as per @djpaul on http://plugins.trac.wordpress.org/ticket/1836 -- don't echo the form until the admin_footer.  Certainly not before <html>!

Fixes #1836, props @djpaul


git-svn-id: https://plugins.svn.wordpress.org/jetpack/trunk@750302 b8457f37-d9ea-0310-8a92-e5e31aec5664