```ruby
# -*- encoding: utf-8 -*-
$:.unshift File.expand_path('../lib', __FILE__)
require 'history_book/version'

Gem::Specification.new do |s|
  s.name        = 'history_book'
  s.version     = HistoryBook::VERSION
  s.authors     = ['John Downey']
  s.email       = ['jdowney@gmail.com']
  s.homepage    = 'http://github.com/jtdowney/history_book'
  s.summary     = %q{HistoryBook is a ruby implementation of the event sourcing pattern.}
  s.description = %q{This library provides an interface for event sourcing over a pluggable back end data store. Currently it supports the Sequel gem and its data stores as well as an in-memory data store for testing.}

  s.files        = Dir.glob('{lib,spec}/**/*.rb') + %w{README.md}
  s.test_files   = Dir.glob('spec/**/*')
  s.require_path = 'lib'

  s.add_dependency 'activesupport', '>= 3.0'
  s.add_dependency 'multi_json', '>= 1.0'

  s.add_development_dependency 'rspec', '~> 2.11'
  s.add_development_dependency 'rake'
  s.add_development_dependency 'sequel', '~> 3.40'
  s.add_development_dependency 'sqlite3-ruby', '~> 1.3'
  s.add_development_dependency 'yajl-ruby', '~> 1.1'
end
```

Add MIT license to gemspec
user
```ruby
# -*- encoding: utf-8 -*-
$:.unshift File.expand_path('../lib', __FILE__)
require 'history_book/version'

Gem::Specification.new do |s|
  s.name        = 'history_book'
  s.version     = HistoryBook::VERSION
  s.authors     = ['John Downey']
  s.email       = ['jdowney@gmail.com']
  s.homepage    = 'http://github.com/jtdowney/history_book'
  s.license     = 'MIT'
  s.summary     = %q{HistoryBook is a ruby implementation of the event sourcing pattern.}
  s.description = %q{This library provides an interface for event sourcing over a pluggable back end data store. Currently it supports the Sequel gem and its data stores as well as an in-memory data store for testing.}

  s.files        = Dir.glob('{lib,spec}/**/*.rb') + %w{README.md}
  s.test_files   = Dir.glob('spec/**/*')
  s.require_path = 'lib'

  s.add_dependency 'activesupport', '>= 3.0'
  s.add_dependency 'multi_json', '>= 1.0'

  s.add_development_dependency 'rspec', '~> 2.11'
  s.add_development_dependency 'rake'
  s.add_development_dependency 'sequel', '~> 3.40'
  s.add_development_dependency 'sqlite3-ruby', '~> 1.3'
  s.add_development_dependency 'yajl-ruby', '~> 1.1'
end
```
assistant