Do not start Android container when there is not android browser in webdriver extension specified

This is related to ARQ-1509 but it is Droidium specific.

When I do have both Android and JBoss adapter classes on class path and when I want to test on regular desktop browser only (meaning browser property in webdriver extension configuration is not set to "android"), there is no need to start Android container so it should not be started.

The solution is to listen to DroidiumExtensionConfigured event. It is fired when some Droidium extension is fired. Extensions are configured before containers are started so that is the right time to remove container def from ContainerRegistry so that Android container will not be started afterwards.