We have to save initial notification action response
in case there isn't registered any FCMNotificationReceived
event handler yet. For example when the app is killed by a user
so JS has to be initialized first. The saved action
response will be sent to JS after first
FCMNotificationReceived event handler registered.

in common error

* IOS: Added identification for which action was taken in case there was many

* Changed the action identifier key to _actionIdentifier

* attempt to fix installation with cocoapods

* Remove unnecessary header imports

Error:

```
Assertion failure in -[GIPReachability startWithCompletionHandler:]
'NSInternalInconsistencyException', reason: 'GIPReachability should be used from the main thread'
```

Fixes #233