Encode special characters in file paths

Karma doesn't encode special characters in file paths, which causes 404 errors if any of your files contain special characters.

For example, create a folder named `({[ ! % & $ # @` ~ ,)}]`, and inside that folder, create a file named`({[ ! % & $ # @ `~ ,)}].js`. Now configure your `karma.conf.js` file to serve this file:

``` javascript
module.exports = function(config) {
config.set({
files: [
'({[ ! % & $ # @ ` ~ ,)}]/({[ ! % & $ # @ ` ~ ,)}].js'
]
});
};
```

Now try running your tests. You'll get a 404 error, because Karma adds the following `` tag to the page, which the browser is unable to resolve.

``` html
<script type="text/javascript" src="/base/({[ ! % & $ # @ ` ~ ,)}]/({[ ! % & $ # @ ` ~ ,)}].js">
```

Instead, the `` tag should look like this:

``` html
<script type="text/javascript" src="/base/(%7B%5B%20!%20%25%20%26%20%24%20%23%20%40%20%60%20~%20%2C)%7D%5D/(%7B%5B%20!%20%25%20%26%20%24%20%23%20%40%20%60%20~%20%2C)%7D%5D.js">
```