Add Android-related files to gitignore

packaging/android/.gitattributes

@@ -0,0 +1,9 @@
+#
+# https://help.github.com/articles/dealing-with-line-endings/
+#
+# Linux start script should use lf
+/gradlew        text eol=lf
+
+# These are Windows script files and should use crlf
+*.bat           text eol=crlf
+

packaging/android/.gitignore

@@ -0,0 +1,11 @@
+# Ignore Gradle project-specific cache directory
+.gradle
+
+# Ignore Gradle build output directory
+build
+
+# Ignore local gradle properties file
+local.properties
+
+# Also ignore the generated assets for Android
+lib/src/main/assets