Default document's oEmbed service to responsive
Default document's oEmbed service to responsive

Embedly requires it, and without either an explicit width/height or responsive:true, our embed code breaks non-full-screen usage by disabling `html/body` scrolling.

Ergo, default oEmbed service to responsive.

ivarvong/documentcloud,Teino1978-Corp/Teino1978-Corp-documentcloud,gunjanmodi/documentcloud,gunjanmodi/documentcloud,Teino1978-Corp/Teino1978-Corp-documentcloud,ivarvong/documentcloud,dannguyen/documentcloud,gunjanmodi/documentcloud,monofox/documentcloud,documentcloud/documentcloud,dannguyen/documentcloud,dannguyen/documentcloud,ivarvong/documentcloud,Teino1978-Corp/Teino1978-Corp-documentcloud,moodpo/documentcloud,monofox/documentcloud,monofox/documentcloud,monofox/documentcloud,Teino1978-Corp/Teino1978-Corp-documentcloud,moodpo/documentcloud,documentcloud/documentcloud,moodpo/documentcloud,documentcloud/documentcloud,documentcloud/documentcloud,ivarvong/documentcloud,dannguyen/documentcloud,moodpo/documentcloud,gunjanmodi/documentcloud