Do not overwrite the user provided payload

Allow users of Notification to provide the full data, including the 'aps' key and its contents.

Specially interesting if you are using the command line tool, and you want to test 'alert' as dictionary with 'loc-key' and 'loc-args'.
Merge pull request #16 from drodriguez/patch-1

Do not overwrite the user provided payload
Bumping version to 0.2.4
Switch to enhanced notification format
Handle dropped connections from APNs automatically
Merge pull request #17 from jcxplorer/dropped-connections

Automatically handle dropped connections from APNs
Bumping version to 0.3.0
Don't require an alert message if content_available (newsstand) is set
Merge pull request #19 from dcaunt/master

Don't require an alert message if content_available (newsstand) is set