```ruby
# -*- encoding: utf-8 -*-
$:.push File.expand_path("../lib", __FILE__)
require "flip/version"

Gem::Specification.new do |s|
  s.name        = "flip"
  s.version     = Flip::VERSION
  s.platform    = Gem::Platform::RUBY
  s.authors     = ["Paul Annesley"]
  s.email       = ["paul@annesley.cc"]
  s.homepage    = "https://github.com/pda/flip"
  s.summary     = %q{A feature flipper for Rails web applications.}
  s.description = %q{Declarative API for specifying features, switchable in declaration, database and cookies.}

  s.rubyforge_project = "flip"

  s.files         = `git ls-files`.split("\n")
  s.test_files    = `git ls-files -- {test,spec,features}/*`.split("\n")
  s.executables   = `git ls-files -- bin/*`.split("\n").map{ |f| File.basename(f) }
  s.require_paths = ["lib"]

  s.add_dependency("activesupport", "~> 3.0")
  s.add_dependency("i18n")

  s.add_development_dependency("rspec", "~> 2.5")
  s.add_development_dependency("rake")
end
```

Update gemspec to allow installing on Rails 4
user
```ruby
# -*- encoding: utf-8 -*-
$:.push File.expand_path("../lib", __FILE__)
require "flip/version"

Gem::Specification.new do |s|
  s.name        = "flip"
  s.version     = Flip::VERSION
  s.platform    = Gem::Platform::RUBY
  s.authors     = ["Paul Annesley"]
  s.email       = ["paul@annesley.cc"]
  s.homepage    = "https://github.com/pda/flip"
  s.summary     = %q{A feature flipper for Rails web applications.}
  s.description = %q{Declarative API for specifying features, switchable in declaration, database and cookies.}

  s.rubyforge_project = "flip"

  s.files         = `git ls-files`.split("\n")
  s.test_files    = `git ls-files -- {test,spec,features}/*`.split("\n")
  s.executables   = `git ls-files -- bin/*`.split("\n").map{ |f| File.basename(f) }
  s.require_paths = ["lib"]

  s.add_dependency("activesupport", ">= 3.0", "< 5")
  s.add_dependency("i18n")

  s.add_development_dependency("rspec", "~> 2.5")
  s.add_development_dependency("rake")
end
```
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