add fabric.properties

Since that is what it should be called now a days according to https://dev.twitter.com/fabric/android/integrating

Global/JetBrains.gitignore

@@ -44,3 +44,4 @@ atlassian-ide-plugin.xml
 com_crashlytics_export_strings.xml
 crashlytics.properties
 crashlytics-build.properties
+fabric.properties