Fixes/Improvements/Adaptions

- DialogFeedback/DialogRateMe
	- they are now saving and restoring their state => no crashes on screen time out/screen rotation/activity recreation
	- button click callback is optional, the parent activity has to handle it => therefore, I renamed the inner callback function to onHandleRateMeAction, so that it's more clear in the parent activity, what the call back does
- string resources prefixed with rate-me
- DialogFeedback
    - extended, so that it uses the button and title colors as well
    - feedback will have a subject like "Feedback for AppName" => string defined in main resource file
- RateMeDialogTimer
	- removed constructor and added the two parameters to the static shouldShowRateDialog function
	- onStart only increases launch time if activity was created, not on screen rotation or activity recreation
- added german translation

Btw., I did not update the readme...
that's how I implemented a optional callback... so the exception should not be called, just silently ignored... the default callback which only prints out some debug informations will be called instead... the comment in the code could be removed of course...