Add Table Snippet

Expands `table` to:

```
| Header One     | Header Two     |
| :------------- | :------------- |
| Item One       | Item Two       |
```

Rather than leaving the cells blank I added tab stops that select the content in each of the cells. I thought tables are probably a less commonly known feature so an empty table might be a bit hard to understand.

![table](https://f.cloud.github.com/assets/475255/2489791/83a044f6-b178-11e3-81c6-62f995a71d06.gif)