Picture element and size

Picture element only uses global attributes, thus width and height does not work. A simple fix to parse out width and height attributes and place them as a style instead.

Changes available (and committed through Github)

https://github.com/wp-media/imagify-plugin/pull/426

https://github.com/wp-media/imagify-plugin/pull/426/commits/af8c5cb84e1f2f6a6b069d6ebdec00d52c9f86b9