Adding back .gitignore file

Change-Id: I22d76bdddb2b5e4a98f6f7f155933de94c40cc6f
diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..7240e48
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,16 @@
+db_files
+*.iml
+.project
+.classpath
+.project.properties
+gen/
+tests/stress/gen/
+WallpaperPicker/gen/
+WallpaperPicker/.project.properties
+bin/
+.idea/
+.gradle/
+local.properties
+gradle/
+build/
+gradlew*
\ No newline at end of file