https://forums.bitfire.at/topic/1190/davdroid-1-3-has-been-released
* use cert4android for better
integration of self-signed certificates (fixes hanging
synchronization when the certificate has changed etc.)
* user-installed CAs will be accepted in
Android 7 again
* new app-wide setting: distrust system
certificates
* clean up permissions
* vcard4android: fix bug concerning
generated formatted postal addresses
* new logo (thanks to Christoph
Scheidl)
* minor optimizations and bug
fixes