svgEl.className is readOnly so live binding does not work

[JaneOri]

SVG elements class name is readOnly so the only way to set it is to use
svgEl.setAttribute( "class", "..." );

This means that this:
<svg class="{{#if cond}}liveBoundClassName{{/if}}"></svg>
does not work.

[justinbmeyer]

fix is to probably sniff out if the element is SVG and change how you set the value.

Basically class here: https://github.com/bitovi/canjs/blob/master/util/attr/attr.js#L41

Should be changed to do setting with a function more like:

https://github.com/bitovi/canjs/blob/master/util/attr/attr.js#L50