Fix exception message formatting

Before:
```
selenium.common.exceptions.WebDriverException: Message: 'ChromeDriver executable needs to be available in the path.                 Please download from http://chromedriver.storage.googleapis.com/index.html                and read up at http://code.google.com/p/selenium/wiki/ChromeDriver'
```

After:
```
selenium.common.exceptions.WebDriverException: Message: 'ChromeDriver executable needs to be available in the path. Please download from http://chromedriver.storage.googleapis.com/index.html and read up at http://code.google.com/p/selenium/wiki/ChromeDriver'
```