Filter out non-Grimoire directories
Filter out non-Grimoire directories

This addresses issue #20.

Solve it in the shortest way possible by just inserting a check whether
a directory at the group level contains a file named meta.edn. If it
doesn't, it either isn't a Grimoire directory or violates the contract
(which I can't find right now), so throw it out.

Not sure if a more complete solution is desired. – Putting the raw
string "meta.edn" in there is not so nice and maybe we should also check
directories below group level? Anyway, this commit does fix the most
common issue.

clojure-grimoire/lib-grimoire