also fixed count behavior according to limit and offset.
fixes #1458

- make use of traits
- short array
- better implementation of query findByPk

- relation support
- completed and refactored lua script builder

- http://redis.io/commands/eval
- http://www.lua.org/

- introduced RecordSchema class for schema definition

relations are not working yet

Added support for scopes defined in AR classes.

finished AR documentation.