Configurable MML

The previous mml file was hardcoded with datasource information specific to one person's machine's database. This PR adds a small configurable ini file which is used to fill out the relevant bits of a templated mml file. This does add the annoyance of anyone changing the mml has to port their changes (sans the datasource configs) back into the template though so maybe this is sub optimal. does anyone else have a suggestion of a cleaner way of doing this?
only real changes to this file are the templatizing of the database parameters so that the cartocc replacements can match on them.