Update CHANGELOG for 2.12.3 (#774)

* Secure information stored in SharedPreferences

* Lower aws-android-sdk-core-test compile and target sdk version to 27

* Add a symlink to android-23.jar for core

* Add a gradle task that creates a symlink to android-23.jar for AWS Core

* Fix the gradle task that creates symbolic link to android-23.jar

* Change config.yml to setup android-23

* Enable core, cognitoidentityprovider and cognitoauth integration tests on CircleCI

* Enable core, cognitoidentityprovider and cognitoauth integration tests on CircleCI

* Fix pom.xml

* Improve exception handling in AWSKeyValueStore

* [2.12.3] Bump the patch version of 2.12.z

* Update 2.12.3 CHANGELOG

Author: Karthikeyan

CHANGELOG.md

@@ -5,19 +5,29 @@
 ### Enhancements
 
 * **AWS Core**
-  * The `SharedPreferences` used by `CognitoCachingCredentialsProvider` is now encrypted. 
+  * Persistence of client state including user credentials is now enabled and encrypted by default.
   * Added a method `CognitoCachingCredentialsProvider.setPersistenceEnabled(boolean)`, which is enabled (set to true) by default therefore the information is persisted in SharedPreferences. When disabled (set to false), the information will only be kept in memory.
 
 * **Amazon CognitoIdentityProvider**
-  * The `SharedPreferences` used by `CognitoUserPool` is now encrypted. 
+  * Persistence of client state including user credentials is now enabled and encrypted by default. 
   * Added a method `CognitoUserPool.setPersistenceEnabled(boolean)`, which is enabled (set to true) by default therefore the information is persisted in SharedPreferences. When disabled (set to false), the information will only be kept in memory.
 
 * **Amazon CognitoAuth**
-  * The `SharedPreferences` used by `Auth` is now encrypted. 
+  * Persistence of client state including user credentials is now enabled and encrypted by default. 
   * Added a method `Auth.setPersistenceEnabled(boolean)`, which is enabled (set to true) by default therefore the information is persisted in SharedPreferences. When disabled (set to false), the information will only be kept in memory.
 
 * **AWSMobileClient**
-  * The `SharedPreferences` used by `AWSMobileClient` is now encrypted.
+  * Persistence of client state including user credentials is now enabled and encrypted by default.
+  * Added an option through `awsconfiguration.json` to disable persistence. **Note:** The Amplify CLI (as of March 8th 2019) does not support this configuration and will remove it when auto-generating the `awsconfiguration.json`.
+    ```
+    {
+      "Auth": {
+        "Default": {
+          "Persistence": false
+        }
+      }
+    }
+    ```
 
 ## [Release 2.12.2](https://github.com/aws/aws-sdk-android/releases/tag/release_v2.12.2)