Merge branch 'vector-compat' into 'master'

briar-android/artwork/notification_signout.svg

briar-android/build.gradle

...project/briar/android/AndroidNotificationManagerImpl.java

...ject/briar/android/conversation/ConversationActivity.java

...java/org/briarproject/briar/android/login/LoginUtils.java

...iarproject/briar/android/navdrawer/NavDrawerActivity.java

...arproject/briar/android/navdrawer/TransportsActivity.java

...ain/java/org/briarproject/briar/android/util/UiUtils.java

...rg/briarproject/briar/android/view/BriarRecyclerView.java

...rproject/briar/android/view/TextAttachmentController.java

...g/briarproject/briar/android/view/TrustIndicatorView.java

...id/src/main/res/drawable-anydpi-v24/notification_blog.xml

...in/res/drawable-anydpi-v24/notification_contact_added.xml

...d/src/main/res/drawable-anydpi-v24/notification_forum.xml

...id/src/main/res/drawable-anydpi-v24/notification_lock.xml

...src/main/res/drawable-anydpi-v24/notification_ongoing.xml

...in/res/drawable-anydpi-v24/notification_private_group.xml

.../res/drawable-anydpi-v24/notification_private_message.xml

...src/main/res/drawable-anydpi-v24/notification_signout.xml

...-android/src/main/res/drawable-hdpi/notification_blog.png