New package: cryptodbm

Request to include a new package into opam repository: cryptodbm.

Project homepage:
https://forge.ocamlcore.org/projects/cryptodbm/

API:
http://cryptodbm.forge.ocamlcore.org/Cryptodbm.html

(FYI, I tried git's sparse-checkout feature to checkout opam packages information. I hope it won't break anything in the official repo. Apparently, everything seems all right - existing packages are untouched).