Update gitignore for new gradle setup

.gitignore

@@ -1,12 +1,13 @@
-.idea/
-captures/
-java/bin/
-java/gen/
-java/hackerskeyboard.iml
-java/libs/*/
-java/local.properties
-java/private.properties
-java/obj/
-out/
-tests/gen/
-tests/tests.iml
+*.iml
+.gradle
+/local.properties
+/.idea
+/.idea/caches/build_file_checksums.ser
+/.idea/libraries
+/.idea/modules.xml
+/.idea/workspace.xml
+.DS_Store
+/build
+/captures
+gradle
+.externalNativeBuild