aasm/aasm — pull request #95 by ivantsepp (2013-11-11 22:28:50+00:00)
Title: Add an ActiveRecord validation

Add a validation to prevent invalid states to persist. So,
```ruby
class Example < ActiveRecord::Base
include AASM
aasm do
state :one
end
end
record = Example.create
record.aasm_state = 'an_invalid_state'
record.save # => false
```
Let me know what you think!