[Android] Change to Android Studio 3 (github#3004)

* ignore all caches

* ignore release folder

Android.gitignore

@@ -13,6 +13,7 @@
 bin/
 gen/
 out/
+release/
 
 # Gradle files
 .gradle/
@@ -41,9 +42,8 @@ captures/
 .idea/assetWizardSettings.xml
 .idea/dictionaries
 .idea/libraries
-.idea/caches
 # Android Studio 3 in .gitignore file.
-.idea/caches/build_file_checksums.ser
+.idea/caches
 .idea/modules.xml
 # Comment next line if keeping position of elements in Navigation Editor is relevant for you
 .idea/navEditor.xml