missing em:unpack Rated 4 out of 5 stars

This dictionary doesn't have an em:pack = true setting that is needed in current Firefox versions that require this.
See https://bugzilla.mozilla.org/show_bug.cgi?id=628932 Bug 628932 - Some dictionaries are not properly installed

<em:name>Serbian Dictionary</em:name>
<em:description>Провера правопиза за српски језик - Serbian (sr) spellchecking dictionary</em:description>

This review is for a previous version of the add-on (0.18).