ENYO-2282: complete plugins load sequence (notify users)

- notify `ProviderList`-s when a plugin is finished loading
  (`pluginReady` invoked)
- fix bugs unveiled by the above in `ProjectProperties.js`
- fix syntax & jshint

Enyo-DCO-1.1-Signed-off-by: Francois-Xavier KOWALSKI <francois-xavier.kowalski@hp.com>