Fluid 5109 - Make pageEnhancer an autoInit component

@amb26, can you review this pull request?

Note that the modified pageEnhancer requires an API change: https://github.com/cindyli/infusion/blob/FLUID-5109/src/demos/uiOptions/js/uiOptionsDemo.js#L48-58

A "uiEnhancer" layer is added to hold initial user options.