Update version and changelog

CHANGELOG.md

@@ -1,6 +1,13 @@
 Change Log
 ---
 
+### 6.4.1 (2019-01-16)
+
+* Limit number of active notifications
+* Limit rate of notifications
+* Fix Synology Calendar sync issue
+* Fix exception when external storage is unavailable
+
 ### 6.4 (2019-01-10)
 
 * Copy backups to Google Drive

app/build.gradle

@@ -19,8 +19,8 @@ android {
     defaultConfig {
         testApplicationId "org.tasks.test"
         applicationId "org.tasks"
-        versionCode 547
+        versionCode 548
-        versionName "6.4"
+        versionName "6.4.1"
         targetSdkVersion 28
         minSdkVersion 16
         testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner"