Changes in example ns according to issue #64

According to conversation in issue #64 there is better to use [] in ns declaration after
special forms (:require, :use) since it's clearly describes data. I think same can be
applied to :import and any other form in ns macro.

I think both forms (short and long) are ok to use in real code.

Short form:

```Clojure
(:require [clojure [string :refer :all]
                   [xml :refer :all]])
```

Long form:

```Clojure
(:require [clojure.string :refer :all]]
          [clojure.xml :refer :all]])
```