Merge pull request #195 from anatoliychakkaev/master

Test case for uniqueness validation
Merge pull request #196 from anatoliychakkaev/master

findOrCreate, misc amends
Merge pull request #197 from anatoliychakkaev/master

Implement schema.extendModel(model, props)
Merge branch 'master' of github1602:1602/jugglingdb