Handling of non-empty UITextFields


Made change in method
+ (id)stepToEnterText:(NSString *)text intoViewWithAccessibilityLabel:(NSString *)label traits:(UIAccessibilityTraits)traits expectedResult:(NSString *)expectedResult;

to support text fields having text entered but are initially not-empty. The current KIF master branch only supports empty text fields. This commit initialised the text to nil before entering text, so that the resulting text is what the user passes in as the 'text' parameter to the method.