Enhance OnceUx Documentation

Rationale

Documentation to support the **OnceUx Plugin** has been poor or
non-existant.  This commit resolves that situation.

Files Changes

BasicOnceUxSampleApp/README.md
* New file to address a brief explanattion on how to use the plugin.

README.md
* Add a short snippet on the **OnceUx Plugin**
Merge pull request #66 from BrightcoveOS/enhance-onceux-docs

Enhance OnceUx Documentation