Ignore whole directory, not only inner contents

`dir/*` style let git ignore files and directories in `dir/`, but not
`dir/` itself.
This cause `git clean -df` to remove `dir/` **with its contents**!

To prevent `git clean -df` to remove data directories (`avatar/`, `file/`,
etc), use `dir/` (or `dir`) style in gitignore.

.gitignore

@@ -1,11 +1,11 @@
-avatar/*
-files/*
-file/*
-local/*
-_darcs/*
-logs/*
-log/*
-run/*
+avatar/
+files/
+file/
+local/
+_darcs/
+logs/
+log/
+run/
 config.php
 .htaccess
 httpd.conf