Running `pod install Firebase/Messaging` results in `[!] Unknown command: 'Firebase/Messaging'` using Cocoapods v1.3.1.
Also, there was a parse error in `HEADER_SEARCH_PATHS = "$(SRCROOT)/../node_modules/react-native/Libraries/PushNotificationIOS/**""$(SRCROOT)/../node_modules/react-native-fcm/ios";`, I was able to fix it by opening `APPNAME.xcodeproj/project.pbxproj`.

Remove override of createJSModules

Fix typo so 'grant' is spelled correctly

in common error

safe FirebaseInstanceId.getInstance() access.

`FirebaseInstanceId.getInstance()` can throw exceptions. For example if Firebase was not initialized.

Fix sound type definition

Delete instanceId function

Documentation update

Support Android activity aliases

Fix type Listner to Listener

Just return the className. The old code didn't work with activity aliases. For example, when launching with `<activity-alias android:name=".SplashActivity" android:targetActivity=".MainActivity" />`, the old code would try to get the class for `SplashActivity` which threw `ClassNotFoundException`.

`android/settings.gradle` is the correct path for React Native v0.45.1

Since of recently in master the unused createJSModules has been removed and ReactPackage's no longer contain the definition of createJSModules. There for it must be removed in order to not yield a compile error. This is breaking change.

https://github.com/facebook/react-native/commit/ce6fb337a146e6f261f2afb564aa19363774a7a8

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