Make DefaultMediaNotificationProvider more customizable

[tzugen]

I want to customize the smallIcon as well as the setShowActionsInCompactView().
Unfortunately I can't extend the DefaultMediaNotificationProvider because it is marked private in the package.

So the only solution I found was to copy the code from DefaultMediaNotificationProvider.java to my project and then change it there.

But that is not very nice, and if upstream it is changed, we won't get the changes.

[marcbaechinger]

Closing as this is fixed and will be included in 1.0.0-beta01 which is on its way to be released.