Use In-Memory SQLite server for spec runs

Out of the box, the CASinoCore specs all fail because there is no configured SQLite database and there are no instructions guiding contributors as to how to create one.

Rather than dealing with writing documentation and supporting the installation of SQLite, etc., I changed the `database.yml` to use an in-memory SQLite database in test mode.

This ensures that all specs run (and pass) out of the box with nothing more complicated than a `bundle install && rspec`

Additionally, I took the liberty of organizing the spec run configurations to make them more explicit. Each gem that requires spec run configuration gets its own support file that "owns" that gem's configuration. That way there is no hunting around for where some option is set.

I was tempted to use an in-memory store for development, but I'm unsure how the rbCAS team's development workflow works. In other projects, I have added some seed data to the `schema.rb` file to pre-populate the in-memory database with specific fixtures in development mode. If there is no specific workflow, I would certainly make the recommendation to go all in with an in-memory database as it simplifies contributing to the project.