Update .gitignore to take into account Gradle auto-import.

.gitignore

@@ -71,13 +71,13 @@ gradle-app.setting
 # When using Gradle or Maven with auto-import, you should exclude module files,
 # since they will be recreated, and may cause churn.  Uncomment if using
 # auto-import.
-# .idea/artifacts
-# .idea/compiler.xml
-# .idea/modules.xml
-# .idea/*.iml
-# .idea/modules
-# *.iml
-# *.ipr
+ .idea/artifacts
+ .idea/compiler.xml
+ .idea/modules.xml
+ .idea/*.iml
+ .idea/modules
+ *.iml
+ *.ipr
 
 # CMake
 cmake-build-*/