Blog post meta descriptions contains first 80 words

Before:

![screen shot 2014-09-19 at 20 57 54](https://cloud.githubusercontent.com/assets/45299/4344149/f94766c6-407a-11e4-94f3-ed488b5ef7b1.png)

After:

![screen shot 2014-09-19 at 21 01 12](https://cloud.githubusercontent.com/assets/45299/4344150/fd916d1c-407a-11e4-877d-2545c1725d3a.png)