helloworld: Update to match helloworld at phones.digium.com

This change brings this helloworld in line with the application at
http://phones.digium.com/phone-api/tutorials/content/printing-hello-world-phones-screen
bigclock: Update the app to the 1.3 firmware interface.

From [1]:

  * A digium.event namespace has been created that replaces the
    previous implementation of registering event callbacks through the
    properties of digium.handlers. Methods were added to digium.event to
    observe, trigger, and stop observing events. This allows multiple
    handlers to subscribe to the same event.

  * Apps control whether they are shutdown when they are hidden with
    digium.app.exitAfterBackground.

[1] http://phones.digium.com/content/phone-api-production-firmware-13-changes-beta-12
menu-example: Update to the 1.3 firmware interface.

From [1]:

  * A digium.event namespace has been created that replaces the
    previous implementation of registering event callbacks through the
    properties of digium.handlers. Methods were added to digium.event to
    observe, trigger, and stop observing events. This allows multiple
    handlers to subscribe to the same event.

  * Apps control whether they are shutdown when they are hidden with
    digium.app.exitAfterBackground.

[1] http://phones.digium.com/content/phone-api-production-firmware-13-changes-beta-12
weather: Update to the 1.3 firmware interface.

From [1]:

  * A digium.event namespace has been created that replaces the
    previous implementation of registering event callbacks through the
    properties of digium.handlers. Methods were added to digium.event to
    observe, trigger, and stop observing events. This allows multiple
    handlers to subscribe to the same event.

  * Apps control whether they are shutdown when they are hidden with
    digium.app.exitAfterBackground.

[1] http://phones.digium.com/content/phone-api-production-firmware-13-changes-beta-12
crm-example: Update to the 1.3 firmware interface.

From [1]:

  * A digium.event namespace has been created that replaces the
    previous implementation of registering event callbacks through the
    properties of digium.handlers. Methods were added to digium.event to
    observe, trigger, and stop observing events. This allows multiple
    handlers to subscribe to the same event.

  * Apps control whether they are shutdown when they are hidden with
    digium.app.exitAfterBackground.

Also, the on_incoming_call handler now needs to get the call information by
looking at the eventData member of the callback parameter.

[1] http://phones.digium.com/content/phone-api-production-firmware-13-changes-beta-12