fill_config.py: sort foreach items numerically, not alphabetically

Make sure that BTS 11 doesn't get sorted between BTS 1 and 2, because osmo-bsc
requires the BTS to be configured in numerical order.

Also makes sense as foreach loop ordering in general.

Change-Id: Ib06052fd71def3d4c869ee9b3dc4d02ba06267af
1 file changed