Merge pull request #2 from paopay/schema_models

fixed schemas and added validations
i don't know, just back from lunch:
added seed
Merge pull request #3 from paopay/jen_kelley

i don't know, just back from lunch:
Merge branch 'master' of https://github.com/paopay/tweeter into schema_models
registration logic complete, post /users
Merge branch 'jen_kelley' of https://github.com/paopay/tweeter into schema_models