Discussion bug fixes

* Fixes #4503 
* Fixes #4113 
* Fixes #4498
* If user's website is "", don't show ([e.g](https://profile.theguardian.com/user/jamesgorrie))

## Para spacing before
![paranospace](https://cloud.githubusercontent.com/assets/31692/3147099/719054e6-ea52-11e3-912f-7fb3bcb15714.png)

## Para spacing after
![paraspace](https://cloud.githubusercontent.com/assets/31692/3147101/789862a6-ea52-11e3-9583-42349845b14f.png)

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![Small things](http://stream1.gifsoup.com/view5/2718689/blink-182-all-the-small-things-o.gif)