dedupe social buttons and min-height for articles

- added minimum height to articles (so ads have enough space to load)
- remove bottom social buttons when article fits easily in the browser window (deduping)

before
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![image](https://cloud.githubusercontent.com/assets/960919/4319152/4f2514de-3f28-11e4-9e31-a278701a599d.png)

after
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![image](https://cloud.githubusercontent.com/assets/960919/4319150/42c66c7e-3f28-11e4-93f0-3848eb2778ee.png)