Optionally disable HTML sanitizing.

rebase or #128

needed to insert this kind of stuff:

```
<a href="https://itunes.apple.com/us/app/depop/id518684914?mt=8&uo=4" target="itunes_store" style="display:inline-block;overflow:hidden;background:url(https://linkmaker.itunes.apple.com/htmlResources/assets/en_us//images/web/linkmaker/badge_appstore-lrg.png) no-repeat;width:135px;height:40px;@media only screen{background-image:url(https://linkmaker.itunes.apple.com/htmlResources/assets/en_us//images/web/linkmaker/badge_appstore-lrg.svg);}"></a>
```