fixed: if no config is saved "small" parcel size is shown as default, so it's better to check for a medium package, else return small. Otherwise users
who have upgraded from an earlier version will be shown "small" package size in the admin panel, yet the code will choose "medium". Alternatively it could have checked for an empty config value
fixed: forgot to change the size logic (it's a hot day and had brain glitch). Instead check for empty config value
Merge pull request #5 from exobuzz/fix_default_size

fixed: if no config is saved "small" parcel size is shown as default, so...