TeeJee.FileSystem.vala: Remove any existing destination file before

attempting to write.

Commit 589c2e5 removed the file.delete() call. Unfortunately
it is documented that the Gio.FileCreateFlags.REPLACE_DESTINATION
flag only works for g_file_replace* methods, not for g_file_create,
so users were getting a 'file exists' error.

Since there's little chance of any sort of race condition here,
just restore the original code, and remove the useless g_file_create
flag so we're not fooled again.

Fixes #491.

Author: mtwebster

src/Utility/TeeJee.FileSystem.vala

@@ -171,7 +171,11 @@ namespace TeeJee.FileSystem{
 			dir_create(file_parent(file_path));
 
 			var file = File.new_for_path (file_path);
-			var file_stream = file.create (FileCreateFlags.REPLACE_DESTINATION);
+			if (file.query_exists ()) {
+				file.delete ();
+			}
+
+			var file_stream = file.create (FileCreateFlags.NONE);
 			var data_stream = new DataOutputStream (file_stream);
 			data_stream.put_string (contents);
 			data_stream.close();