Add the notification channel for compatible with Android oreo

[gongmingqm10]

No description provided.

[Gp2mv3]

I'll close this PR as I merged the previous one with the exact same changes (#657)

[Dhanraj-bidchat]

i believe this is android Oreo[target version >= 27] issue.
Two methods to resolve this:
1)Downgrade your android targetSdkVersion to 26 or less under 'android/app/build.gradle'.
2)I forked and fixed this. You can add this in your projects package.json :
"react-native-push-notification": "git+https://github.com/Dhanraj-bidchat/react-native-push-notification.git" and remove 'react-native-push-notification: ''3.0.1',
Then delete react-native-push-notification under node_modules
Then run npm install.
@Gp2mv3