Synced gitignores with github repo (#1245)

* Renamed scripts directory into contrib

* Added script to download gitignores from github

* Synced gitignores with github repo

options/gitignore/Android

@@ -2,7 +2,7 @@
 *.apk
 *.ap_
 
-# Files for the Dalvik VM
+# Files for the ART/Dalvik VM
 *.dex
 
 # Java class files
@@ -11,6 +11,7 @@
 # Generated files
 bin/
 gen/
+out/
 
 # Gradle files
 .gradle/
@@ -30,3 +31,25 @@ proguard/
 
 # Android Studio captures folder
 captures/
+
+# Intellij
+*.iml
+.idea/workspace.xml
+.idea/tasks.xml
+.idea/gradle.xml
+.idea/dictionaries
+.idea/libraries
+
+# Keystore files
+*.jks
+
+# External native build folder generated in Android Studio 2.2 and later
+.externalNativeBuild
+
+# Google Services (e.g. APIs or Firebase)
+google-services.json
+
+# Freeline
+freeline.py
+freeline/
+freeline_project_description.json