Squashed commits
Update .travis.yml

ADDED gems: 'device' and 'enumerize' && bundle install
		model User and migration
		valid factory for User and test

ADDED gems: 'device' and 'enumerize' && bundle install
		model User and migration
		valid factory for User and test

question functionality

passing tests

answers functionality

removed has variants functionality

added has_variants functionality

Changed db/schema.db for previous fixies

updated association for user
[Почему reference вместо foreign key](http://stackoverflow.com/questions/11535025/difference-between-foreign-key-constraint-and-references-in-rails)

Settuped association in survey factory

Settuped association in answer factory, deleted creating user_id, added belons_to :user

Added Variants functionality

Answer belongs_to user now, fixed association in factory girl

FIXED missing tests in spec/models

Fixed factories for answer and variants

RENAMED property of Answer from user => answerer, for more clarity, and just not to mess up

DELETED has_values in Questions table
UPDATED kind type to enumerable
ADDED has_variants? method to Question

Update README.md

Update .travis.yml