Decide version of CiviCRM to target

CiviCRM 4.5 introduces a ton of improvements to the JavaScript framework. Targeting 4.5 would make for:

• easier development
• less code to maintain
• a better user experience

However, it means we might leave some folks behind, as upgrading is not a trivial matter for some organizations. That's certainly an important benefit, but coding to 4.4.x means there will be duplication of effort in adapting the new functionality to work with 4.5, as we don't want to pin folks to 4.4.x in order to keep their volunteer functionality.