Adding UnexpectedAlertPresentException to python bindings

Signed-off-by: AutomatedTester <dburns@mozilla.com>
Bump webdriverjs version to 2.32.0-dev
Using a DesiredCapabilities to control WDBS won't always work since the
user may not have access to the capabilities (or the driver won't implement
HasCapabilities). Add a method to WebDriverCommandProcessor to control
whether to emulate Selenium's alert API.
updating alert tests to 'wait' for alert to appear. iOS alerts appear asynchronously.