 * Add simple crash reporter (by opening the mail app with the error message)
 * Fix crash by asking for WRITE_EXTERNAL_STORAGE and READ_EXTERNAL_STORAGE permissions
 * Show progress bar when verifying the downloaded APK
 * Download APK to the public download directory of the app (for example: /storage/sdcard0/Android/data/de.marmaro.krt.ffupdater/files/Download)
 * Remove old debug messages
 * Thanks yhoyhoj, UltraBlackLinux, rvandegrift, vikajon, wchen342, Ulfschaper, prox and danceswithcats for your error reporting