fix #1367 use `expando.value` instead of deprecated `.nodeValue`

Chrome and Firefox dev tools log deprecation message of `.nodeValue`
which may unnecessarily pollute applications' logs.

The alternative `.value` seems to be supported by all browsers
(tested down to Firefox 3 and IE7)
fix #1372 Storage event issue

This commit makes sure storage events do not cause errors when the stored
values are not JSON, or when events are not listened to.
fix #1373 Use "section" statement as a container

This commit re-introduces the possibility to use the `section` statement as a container ({section {...}}...{/section}).
Since the `macro` property is not mandatory, it is also possible to provide a string argument to the statement ({section "mySectionId"}...{/section}).

This feature is disabled by default. In order to enable it, you need to set an application environment variable:
```
aria.core.AppEnvironment.setEnvironment({
    templateSettings : {
        dangerouslyAllowSectionsAsContainers : true
    }
});
```