Add file creation test

Ensure that iniadd is creating files that don't exist, as it has
historically done.

Change-Id: I2798996f3d46ff1dce410b815a87395f1bf729f9
diff --git a/inc/ini-config b/inc/ini-config
index d23f474..58386e2 100644
--- a/inc/ini-config
+++ b/inc/ini-config
@@ -159,6 +159,7 @@
 
 # Set an option in an INI file
 # iniset [-sudo] config-file section option value
+#  - if the file does not exist, it is created
 function iniset {
     local xtrace=$(set +o | grep xtrace)
     set +o xtrace