make the <a> tag the parent of the target to add hrefs to everything

This is a fix for the following sprout:
http://www.share-elm.com/sprout/53b117d1e4b07afa6f982635

As first noticed by Do Bi.

I tried to keep this change pixel perfect but there may be a weird case I overlooked. See if you can break this.
Using absolute breaks flows (i.e., [original bug](http://www.share-elm.com/sprout/53b27285e4b07afa6f98270b))

Original version
![0 12 3](https://cloud.githubusercontent.com/assets/1889997/3441046/8ebf9df6-00ff-11e4-90c3-0361ea3b2c56.png)

Position: absolute
![position-absolute](https://cloud.githubusercontent.com/assets/1889997/3441052/a39eb81a-00ff-11e4-84f2-63126fa3eccf.png)

Position: relative
![position-relative](https://cloud.githubusercontent.com/assets/1889997/3441054/a9685832-00ff-11e4-9492-436bf61d0447.png)


I now notice the link line in the direct comparison.