closes #72
Merge pull request #73 from AlexKolpa/#72_Gradle_update

:+1: with one request: next time, a little more info in the title about (added) functionality.
Merge branch 'master' of https://github.com/AlexKolpa/AndroidStealth into Pin_dialog
Fixes based on comments of @jzvandenoever, and added some extra delete methods as those should also have been included:
- fixed the long string creation
- added method m(String message) in order to log a standard message without the stacktrace element attached
- fixed a few comments
- added the deleteNonMedia() and deleteAudio() method and included them in the delete() method.
- added isAudio() check in FileUtils.java
Found a bug that wrong elements were actually removed from the index because I didn't yet set the correct JSON id's when reading the preferences, and I also set the wrong one when adding a file/folder. Now it should work perfectly. Also, seemed that after deleting a file from the mediastore, it is possible that the file itself is not actually gone (had it with PDF files), so I do an extra check to see if the file is indeed gone, if not I delete in the casual way. Now that works too :)