Add gitignore

Author: Sylwester Sokołowski

app/.gitignore

@@ -1 +1,43 @@
 /build
+### Android template
+# Built application files
+*.apk
+*.ap_
+
+# Files for the ART/Dalvik VM
+*.dex
+
+# Java class files
+*.class
+
+# Generated files
+bin/
+gen/
+out/
+
+# Gradle files
+.gradle/
+build/
+
+# Local configuration file (sdk path, etc)
+local.properties
+
+# Proguard folder generated by Eclipse
+proguard/
+
+# Log Files
+*.log
+
+# Android Studio Navigation editor temp files
+.navigation/
+
+# Android Studio captures folder
+captures/
+
+# Intellij
+*.iml
+.idea/workspace.xml
+
+# Keystore files
+*.jks
+