Append this._storageSuffix (which includes API key) to unsentKey before storing in AsyncStorage

Currently, when saving events to AsyncStorage, we we are only using unsentKey as the identifier.
This can cause events from multiple projects to get mixed up. By appending this._storageSuffix,
we are adding more specificity to keep unsent events within the correct project scope.

Author: sputh

src/amplitude-client.js

@@ -168,7 +168,7 @@ AmplitudeClient.prototype.init = function init(apiKey, opt_userId, opt_config, o
     if (AsyncStorage) {
       Promise.all([
           AsyncStorage.getItem(this._storageSuffix),
-          AsyncStorage.getItem(this.options.unsentKey),
+          AsyncStorage.getItem(this.options.unsentKey + this._storageSuffix),
           AsyncStorage.getItem(this.options.unsentIdentifyKey),
       ]).then((values) => {
         if (values[0]) {
@@ -702,7 +702,7 @@ AmplitudeClient.prototype._saveReferrer = function _saveReferrer(referrer) {
 AmplitudeClient.prototype.saveEvents = function saveEvents() {
   try {
     if (AsyncStorage) {
-      AsyncStorage.setItem(this.options.unsentKey, JSON.stringify(this._unsentEvents));
+      AsyncStorage.setItem(this.options.unsentKey + this._storageSuffix, JSON.stringify(this._unsentEvents));
     } else {
       this._setInStorage(localStorage, this.options.unsentKey, JSON.stringify(this._unsentEvents));
     }