Removes IIFE patterns in source.

Ain't nothin' wrong with an IIFE, but by removing them our Object definitions become slightly more consistent across the codebase. Which is a big :+1: to me.

This gets rid of the IIFE around RegionManager per @paulovieira's suggestion. While I was at it, I also got rid of the one around `triggerMethod` (with the added bonus of removing an unnecessary argument passed to it).

Behaviors is the last one with an IIFE...but that code is basically a mess. It's a big enough refactor to merit its own PR.
You could also clean this up:
```js
function handleRender() { // removing `view` argument allows you to unwrap the listener below
  view._isRendered = true;
  triggerDOMRefresh();
}

function handleShow() { // removing `view` argument allows you to unwrap the listener below
  view._isShown = true;
  triggerDOMRefresh();
}

function triggerDOMRefresh() {
  if (view._isShown && view._isRendered && Marionette.isNodeAttached(view.el)) {
    if (_.isFunction(view.triggerMethod)) {
      view.triggerMethod('dom:refresh');
    }
  }
}

view.on({
  show   : handleShow,
  render : handleRender
});
```