* use cert4android instead of MemorizingTrustManager
* new app setting: distrust system certificates
* add network security config to manifest so that user-installed CAs will be accepted in Android 7 again
* update gradle
* task list synchronization: don't set VISIBLE=1 and SYNC_ENABLED=1 at every sync, but only at creation
* task list synchronization: sync only task lists which are SYNC_ENABLED
* honor "manage calendar colors" account setting for task list colors, too
* add run-tests-connected.sh, to be used as pre-commit hook
* ical4android/vcard4android tests
* fetch translations from Transifex
* version bump to 1.0.7
* increase target API level to 23 (Android 6), which makes Android 6-style permissions mandatory
* AUTHENTICATE_ACCOUNTS permission is only required up to API level 22
* new activity: PermissionsActivity which shows missing permissions and provides buttons to request them
* DavService: Android shouldn't send a null Intent, but sometimes it does, so implement null check
* LocalTaskList: tasksProviderAvailable may return true on API level 23+ even if permissions are not sufficient
* SyncAdapterService: show a notification (with Intent for PermissionsActivity) when permissions are not sufficient
* when creating accounts, set OpenTasks sync always to true if API level is 23+ (even if OpenTasks is not installed [yet])
* update Lombok
* new Settings activity
* Settings: display/change user name, password, preemptive auth.
* Settings: display/change sync. interval for contacts and calendars
* requires permission GET_ACCOUNTS to list accounts in Settings
* requires permission READ_SYNC_SETTINGS to display current sync intervals
* remove obsolete files from res/
* update copyright notices
* version bump to 0.7
* moved all dependencies to gradle instead of shipping .jar files in the app/lib directory
* switched to official Android port of HttpClient instead of httpclientandroidlib
* new .gitignore and project files
