Update all logos

briar-android/artwork/logo_circle.svg

briar-android/artwork/logo_horizontal_white.svg

briar-android/artwork/logo_no_text.svg

briar-android/artwork/logo_vertical_black.svg

briar-android/src/main/AndroidManifest.xml

briar-android/src/main/ic_launcher_round-web.png

briar-android/src/main/res/drawable-hdpi/logo.png

briar-android/src/main/res/drawable-ldpi/logo.png

briar-android/src/main/res/drawable-mdpi/logo.png

briar-android/src/main/res/drawable-xhdpi/logo.png

briar-android/src/main/res/drawable/briar_logo_large.png

...ndroid/src/main/res/drawable/navigation_drawer_header.png

...ndroid/src/main/res/drawable/navigation_drawer_header.xml

briar-android/src/main/res/drawable/splash_screen.xml

briar-android/src/main/res/layout/navigation_header.xml

briar-android/src/main/res/layout/splash.xml

briar-android/src/main/res/mipmap-hdpi/ic_launcher_round.png

briar-android/src/main/res/mipmap-mdpi/ic_launcher_round.png

...r-android/src/main/res/mipmap-xhdpi/ic_launcher_round.png

...-android/src/main/res/mipmap-xxhdpi/ic_launcher_round.png