Fix type Listner to Listener

Thank you for the nice library.
Fixed typo to sample source code.

Update README.md

Fix call to setApplicationIconBadgeNumber

added big picture style to android notification

Recommend staying on iOS SDK v3

Provide collapse_key, from, mesage_id, and send_time in foreground notificaitons

doc(readme) : add missing settings

Update README.md

Update READ.ME with correct diff for dependencies

by just adding a key called picture to  the notification payload, we can
display image on android notification.