Add Support for Storing Values as Strings in the Database

This should add support for, optionally, storing values as strings in the database, via a new initialization argument, 'integer', which defaults to true, so default behavior remains as-is. As part of this update, I created a couple utility methods: one to do default dialect class lookup (along with a new settings variable to use to specify one) and another to format an EUI instance using a specified dialect. I also added some documentation of new functionality to the README along with some release notes outlining the changes.