improve umbraco ignores

Umbraco.gitignore

@@ -1,9 +1,17 @@
-# Ignore Umbraco folders (Generated folders created by Umbraco)
-ClientDependency/
-TEMP/
-Logs/
+# Make sure to include ignores from VisualStudio.gitignore if developing on Umbraco using Visual Studio
+
+# Ignore unimportant folders generated by Umbraco
+**/App_Data/ClientDependency/
+**/App_Data/ExamineIndexes/
+**/App_Data/Logs/
+**/App_Data/[Pp]review/
+**/App_Data/TEMP/
 Cached/
-ExamineIndexes/
 
 # Ignore Umbraco content cache file
-umbraco.config
+**/App_Data/umbraco.config
+
+# Don't ignore Umbraco packages (VisualStudio.gitignore mistakes this for a NuGet packages folder)
+# Make sure to include details from VisualStudio.gitignore BEFORE this
+!**/App_Data/[Pp]ackages/
+!**/[Uu]mbraco/developer/[Pp]ackages