Merge pull request #51 from EnOD/master

Add example of usage shared_examples in RSpec tests
Replace faker gem with ffaker

ffaker is a drop-in replacement for faker that's up to 20x faster at
generating fake data.
Merge pull request #52 from patricklewis/faker-to-ffaker

Replace faker gem with ffaker
fixed #53 - mentioned the better_errors gem
mentioned bullet
mentioned globalize3
Added some missing "do" keywords.
Merge pull request #54 from vakuum/pr-1

Added some missing "do" keywords.
Rephrase the one init file per gem rule
Fix #29 - suggest standard structure for model classes
Add an example of sexy validations usage
Suggest a location for custom validator classes
Refresh the section on migrations