Adding functions to get the larger video thumbnail from YouTube if available.
Merge branch 'master' into max-images
Adding CSS and JS file structures and other necessary functions for an options page.

Added the option to switch from iFrame embeds to Image based embeds.

Calculated the necessary ratios for Vimeo thumbnails which are always 4:3 unlike YouTube which are typically the original ratio of the video 4:3 or 16:9.
Adding basic image embed functionality

Abstracting image and iFrame embed code into their own element files.
Adding basic browser sniffing

even though browser sniffing is bad, I'm not sure how else to do this
check given the idiosyncrasies of the HTML5 players on Android and iOS,
plus the varied support of the YouTube and Vimeo APIs.
Merging the max-images changes and resolving a conflict
Cleaning up the max images code