Updated .gitignore.

.gitignore

@@ -1,4 +1,40 @@
-.gradle
-/local.properties
-/.idea
-/build
+# built application files
+*.apk
+*.ap_
+
+# files for the dex VM
+*.dex
+
+# Java class files
+*.class
+
+# generated files
+bin/
+build/
+gen/
+libs/
+obj/
+.gradle/
+
+# Local configuration file (sdk path, etc)
+local.properties
+project.properties
+
+# Eclipse project files
+.settings/
+.classpath
+.project
+
+# Proguard folder generated by Eclipse
+proguard/
+
+# Intellij project files
+*.iml
+*.ipr
+*.iws
+.idea/
+
+# Gradle wrapper
+gradle/wrapper/gradle/
+gradle/wrapper/gradlew*
+