Add emoji images (generated from `rake gemojione:sprite`)

app/assets/images/emoji/100.png

app/assets/images/emoji/1234.png

app/assets/images/emoji/1F627.png

app/assets/images/emoji/8ball.png

app/assets/images/emoji/a.png

app/assets/images/emoji/ab.png

app/assets/images/emoji/abc.png

app/assets/images/emoji/abcd.png

app/assets/images/emoji/accept.png

app/assets/images/emoji/aerial_tramway.png

app/assets/images/emoji/airplane.png

app/assets/images/emoji/airplane_arriving.png

app/assets/images/emoji/airplane_departure.png

app/assets/images/emoji/airplane_small.png

app/assets/images/emoji/alarm_clock.png

app/assets/images/emoji/alembic.png

app/assets/images/emoji/alien.png

app/assets/images/emoji/ambulance.png

app/assets/images/emoji/amphora.png

app/assets/images/emoji/anchor.png