These are relatively new, the crashlytics.properties file contains the secret and can [alternatively](https://plus.google.com/+AntonioBertucci/posts/S9krjvXfgfm) contain the apikey to rid your repo of the extra strings file.
@@ -42,3 +42,7 @@ atlassian-ide-plugin.xml
# Crashlytics plugin (for Android Studio and IntelliJ)
com_crashlytics_export_strings.xml
+# Crashlytics Secret Location
+**/crashlytics.properties
+# High-Churn file
+**/crashlytics-build.properties
Thomas Hunsaker