smw.sh fails on OS X

[csik]

The script failed early in a few places, for instance trying to download mediawiki itself:
curl -fSL https://releases.wikimedia.org/mediawiki//mediawiki-.tar.gz -o mediawiki.tar.gz

It became clear that environment variable were empty.

I went ahead and ran this before running the smw.sh:

set -o allexport
source vars.env
set +o allexport

Seems to build well now!