Fix leiningen detection in osx_deps.sh.

Current osx_deps.sh reports that Leiningen 2.2 is an old (1.x or 2.0) version. This changeset is a trivial tweak to make the version number detection a bit more robust.
Merge pull request #1209 from manutter51/fix-leiningen-detection

Fix leiningen detection in osx_deps.sh.