New MongoDB formula, rewritten to use official packages and APT repo

Mostly a rewrite to use the official mongodb packages so we can use 2.6.5.

Also have tidied up and automated (tho still needs work) the admin user creation, and normal user creation.

There are helpers for replica set creation, and reindexing, recovery.

So without these includes if you have a highstate that just includes the mongo formula then this would give you errors like "cannot extend state firewall-apply because it is not part of the highstate" so we've already got the dependencies.

I agree that it's not ideal but I'd rather have this than an obscure error in some circumstances (specifically this will break on kitchen tests)