Implemented stepToClearTextInViewWithAccessiblityLabel: to clear text from a populated view using setText:
fixed numerous bugs with scrollview kif additions
Implementing stepForViewWithAccessibilityLabel

This is for executing arbitrary interaction and verification logic on
a given view. Only the accessibility label can be specified, as
verification against the traits and value can be done manually on the
view in the execution block.
Scroll to the element using _accessibilityElementWithLabel:...

If the element is not visible, the UIView will probably not exist and the
executionBlock will get the UIView that is visible and nearest to the
accessibility element in the hierarchy. This is not easy for the block to
predict and deal with, so use |_accessibilityElementWithLabel:| to make the
UIView visible.
Ensure that Tear Down Steps are always executed. fixes square/KIF#161
Add support for using Blocks that return an NSString for the Accessiblity Label and Accessibility Value to test with dynamic values