Ruby 1.9+ symbols not always interpreted

The following code is not correctly highlighted:

``` ruby
%i(this is an array of symbols)
hash = { answer: 42 }
link_to 'new', new_article_path, class: 'btn'
```

* `%i(...)` and `%I` should render like `%w(...)` and friends
* `answer:` should render like a symbol
* `class:` should also render like a symbol, not like the keyword `class`