Allow the option to choose the browser list to get

As noted here
https://saucelabs.com/docs/rest#information
```
Returns an array of strings corresponding to all the browsers currently supported on Sauce Labs. (Choose the termination that defines which list you need, bearing in mind that Selenium 1 [RC] and 2 [WebDriver] are compatible with different browser/OS combinations.)
Relative URLs: /info/browsers/all, /selenium-rc, /webdriver
```
Merge pull request #39 from alnutile/patch-1

Allow the option to choose the browser list to get