Create migrations to change DB schema.
Update Snp model to reflect new migrations.
Add prototype of SnpAdaptor class.
Install rspec.
Install FactoryGirl. Create custom factories. Create some tests.
Change SnpAdaptor responsibilities. Change DB schema. Create some tests.
Add uniqueness to DB schema. Change model to represent the DB schema.
Add set_defaults to Snp.
Finish SnpAdaptor (for now at least).