html: Never add an id attribute to the <img tag
Add an option to make <img tag use jquery lazyload

when --img-lazyload switch is given the <img tags will look like this:
<img data-src="url" src="">

instead of the traditional <img src="url">
html: Respect HTML5 spec for <img tag

Don't append slash before the end of the tag
ex: <img src=""> instead of the old <img src="" />

Signed-off-by: Nyx0uf <benjgodard@me.com>
html: Change handling of width/height for <img tag

Before the output used CSS like this

<img src="" style="width:w;height:h;">

Now it uses the <img tag attributes

<img src="" width="w" height="h">

Signed-off-by: Nyx0uf <benjgodard@me.com>