Jetpack: ensure VideoPress scripts are loaded when using Infinite Scroll.

The VideoPress module's player requires certain scripts to be present to function properly, and those scripts expect to be loaded before `document.ready` fires. While Infinite Scroll does attempt to load additional scripts required by incoming posts, VideoPress's scripts aren't compatible with that loader. As a result, we must always load VideoPress's scripts when IS is present.

In r631532, handling for the standalone VideoPress plugin was added, but the same consideration wasn't implemented when the VideoPress module was introduced in Jetpack 2.5.


git-svn-id: https://plugins.svn.wordpress.org/jetpack/trunk@815060 b8457f37-d9ea-0310-8a92-e5e31aec5664