Turn full words in body keywords into links

See http://www.theguardian.com/world/2014/mar/21/eu-mobilises-trade-war-russia-crimea-ukraine

"Europe" keyword was detected in a paragraph, but "Europe" in "**Europe**an" was turned into a link. This PR fixes that behaviour.

## Before

![screen shot 2014-03-24 at 11 28 29](https://f.cloud.github.com/assets/85783/2498571/16efd714-b348-11e3-82b7-31b187f5afef.PNG)


## After

![screen shot 2014-03-24 at 11 28 20](https://f.cloud.github.com/assets/85783/2498572/199898fc-b348-11e3-8962-c63b336a4c55.PNG)


![ ](http://media.giphy.com/media/FB41CON30OeqI/giphy.gif)