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...
Have a look at the convention we use in our code:

```
new RateMeOnActionListener() {
}
```