gitignore: ignore complete .idea directory

.gitignore

@@ -1,12 +1,7 @@
 *.iml
 .gradle
 /local.properties
-/.idea/caches
+/.idea
-/.idea/libraries
-/.idea/modules.xml
-/.idea/workspace.xml
-/.idea/navEditor.xml
-/.idea/assetWizardSettings.xml
 .DS_Store
 /build
 /captures