Import components for building autocomplete controls

The ProgressiveDataSet already sees usage in:

• Bamboo (for the assign responsibility SingleSelect control)

• FECRU (for mentions in comments)

• JIRA (for mentions in comments)

After pulling in to AUI, it would be prudent to get further input and feedback from all existing users of the component(s) to decide if there are any API changes or additions that should be made.

You'll note there's a lot of commits. That is because I actually mimic'd the aui repo structure in my own repo, then grafted it on here. Fully annotated history ftw!