Revert "Update for XCTest in XCode 6."

This reverts commit 78a44e1243fb94bf8517812a841fc634f8f5815c.
Added NSMutableDictionaryBlock.
Tidy.
Remove unnecessary anonymous interfaces.
Don't allow title=nil for UIAlertView -- it looks rubbish on iOS 8 beta 5.

Instead, make it the empty string.

Also, merge four implementations of showWithXyz, which can all be implemented
in terms of each other.
Tidy.
Move the code to set the parentView for the alert buttons into
UIAlertViewHelper.setButtons:forAlert:

This way, it's not being done in 4 places.