Based on http://guides.rubyonrails.org/association_basics.html#bi-directional-associations and http://guides.rubyonrails.org/association_basics.html#polymorphic-associations, I have updated models specifications, added inversed properties.
RENAMED property of Answer from user => answerer, for more clarity, and just not to mess up
RENAMED property of Answer from user => answerer, for more clarity, and just not to mess up
FIXED Random bug, when password less than 8 characters
DELETED has_values in Questions table
UPDATED kind type to enumerable
ADDED has_variants? method to Question
Merge pull request #22 from tetianahogg/changing_answer

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