Adds a cookie to your current session.
:Args:
- cookie_dict: A dictionary object, with required keys - "name" and "value";
optional keys - "path", "domain", "secure", "expiry"
Usage:
driver.add_cookie({'name' : 'foo', 'value' : 'bar'})
driver.add_cookie({'name' : 'foo', 'value' : 'bar', 'path' : '/'})
driver.add_cookie({'name' : 'foo', 'value' : 'bar', 'path' : '/', 'secure':True})