Moved file and path related methods from StringHelper to FileHelper, renamed StringHelper byte methods not to be misused as string methods

- allows to have dynamic definition of attributes depended on the
  instance
- there was no real need for it to be static. Places that used it static
  have been refactored.

fixes #1318

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

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

- introduced RecordSchema class for schema definition

relations are not working yet

insert update delete