Added support for removing pragmas that are in block comments

Why I add this is because I want to use groundskeeper together with CoffeeScript. In CoffeeScript you cannot produce single-line JS-comments.

The best you can do in CS is:

```coffeescript
    ###<pragma>###
    logicThatShouldBeRemoved()
    ###</pragma>###
```

Which produces JavaScript:

```js
    /*<pragma> */
    logicThatShouldBeRemoved();
    /*</pragma> */
```


Now it ignores the `comment.type`, trims the whitespace off `comment.value` and compares with that.