Remove columns from generated Product model
Fix define hydra attribute methods for sub models
Merge branch 'master' of github.com:kostyantyn/hydra_attribute
Update CHANGELOG.md
Fix typo
Add gemfiles to .gitignore
Generate gemfiles for travis env
Lock activerecord dependency on version 3.x
Add notices to README about stability of current version
Add gem version to README
Create lightweight HydraValue model
Move entity modules to hydra_entity namespace
Create lightweight model implementation

HydraAttribute::Model is a lightweight representation
of ActiveRecord::Base model
Remove database_cleaner gem
Try to resolve travis' issue "syntax error" during performing sql query

Seems it cannot perform multi-insert query
Add auto generation attribute methods for HydraAttribute::Model
Add tests for identity map

- HydraAttribute::IdentityMap
- HydraAttribute#identity_map
- HydraAttribute::Model::IdentityMap
Add possibility for creating nested indentity map objects
Add #save method for Model
Create Mediator for observing models