Display keywords at the end of articles (tags)

[DO NOT MERGE]


## Original Design

The original design looked something like this:
![screen shot 2013-09-16 at 17 49 46](https://f.cloud.github.com/assets/85783/1150773/037fd6bc-1ef0-11e3-9580-2c481ca31698.PNG)


But it does not play well with large numbers of keywords when in a real-world situation:

![screen shot 2013-09-16 at 16 53 03](https://f.cloud.github.com/assets/85783/1150768/e6882122-1eef-11e3-9856-3efc42c46912.PNG)

## Proposed design

With comma separated keywords, we eliminate the issue of having lines that start or end with a pipe character:

![screen shot 2013-09-16 at 16 53 56](https://f.cloud.github.com/assets/85783/1150778/1949eb40-1ef0-11e3-95e0-d7bd30ddf5db.PNG)

![ ](http://s2.developerslife.ru/public/images/gifs/23b6e61e-5e56-4f8e-b45c-f31a5433e2df.gif)