Resolved issue #294

If the view conforms to UITextInput, select the whole content and
delete it.
Add failing test to expose bug in -[UIScrollView scrollViewToVisible:animated:].
Fix bug in [UIScrollView scrollViewToVisible:animated:] that improperly
set UIScrollView's contentOffset when the accessibility element is not
fully onscreen.
Increases specificity of setOn:... to expect a button, since it is the default trait and it reduces failured on diplicates.
Defined the `_touchesEvent` selector for the compiler.

Resolves #285 and #289.
Merge pull request #312 from talko/scrollviewfix

Failing test and fix for bug in [UIScrollView scrollViewToVisible:animated:]
Exposed methods for waiting for views based on accessibilityIdentifier or *any* predicate.

Predicates provide a clean way to test specific details of an object
while still providing a clear error message on failure.  Accessibility
identifier is a trival case of this, but I use it multiple places for
the `instancesRespondToSelector:` test, and lots of people want it.
[tester tapStatusBar]

Introduced a method to tap the status bar.  Resolves #306.