Create button item array on demand, making sure it's non-nil.

When the alert view is created without using the init method in the category the button items array would be nil, causing the actions associated with new RIButtonItems to not fire. Also sets the delegate if needed.
Revert Xcode whitespace cleanup per Jiva.
Fix indentation and method signature spacing to match style.
Merge pull request #40 from dillan/master

Create button item array on demand, making sure it's non-nil.