Stubbed dialogs show extended info

With next branch current as of today (2014-04-26), unit tests failed on my machine on 

 `com.eviware.soapui.support.editor.inspectors.auth.OAuth2ScriptsEditorTest#showsErrorMessageWhenInvalidScriptIsTested`

because my locale is in French and thus the message from javascript validation is longer thant the limit in `UISupport.EXTENDED_ERROR_MESSAGE_THRESHOLD` which triggers a call to `showExtendedInfo()` instead of `showErrorMessages()` and since the former stub in StubbedDialogs is empty, the message is not added to `errorMessages` and the test fails.

Thi pull request fixes this by stubbing showExtendedInfo() : when title is "Error", errorMessages is assigned the text of message.