Fix EZP-23301: Upgrade to YUI 3.17.2
Merge pull request #111 from ezsystems/ezp-23301_yui_3712

Fix EZP-23301: Upgrade to YUI 3.17.2
Update sentences to reflect better the actions
Update DemoContext and ContentContext
Fix/improve demo sentences
Update files structure/namespaces
Add file headers and explanations