- Fix issues with primary key length
  - Added checks for adapter type (postgres, mysql2, ...) when code paths diverge
  - Added mysql-specific and generic non-postgres initial load scripts
  - Added mysql-specific and (untested) generic non-postgres check for duplicate key error. Used to check if the oplog has changed since the last run

  - Added the ability to specify column as an index, null or not null, and a default value
  - Condensed initial input copy to only use the INSERT syntax for all non-postgres adapters
  - Improved readme documentation

 - Added the ability for the mongo instance being read from to be a replica slave