NOJIRA : allow side widgets use by plugins

new hook for getHTMLWidgets() to allow side widgets use by plugins controllers, made looked at getHTMLMenuBar() hook already in place

Sample code for widget insertion in the plugin : 		
```
		public function hookRenderWidgets($pa_widgets_config) {
			$pa_widgets_config["museesDeFranceRecolementInfo"] = array(
				"domain" => array(
					"module" => "museesDeFrance",
					"controller"=>"Recolement"),
				"handler"=> array(
					"module" => "museesDeFrance",
					"controller" => "Recolement",
					"action" => 'Info',
					"isplugin" => true),
				"requires" => array(),
				"parameters" => array()
			);
			return $pa_widgets_config;
		}
```
The method Info is then used to render a view.
Note : the isplugin is important as it tweaks the path to search the controller in plugins dir.

![capture decran 2014-01-05 a 12 41 50](https://f.cloud.github.com/assets/314697/1846493/6b14b3aa-75fe-11e3-9eb0-13a94a89b838.png)