Handle MonetDB authentication somehow

[eyalroz]

At the moment, the DB creation script completely ignores the issue of authentication to the MonetDB server. What this means is that either the user has taken care of that in his/her ~/.monetdb file, or s/he will be prompted for credentials whenever mclient is called. The latter option is incredibly annoying when we have dozens and dozens of files to load.

So, we should probably do something about it.