namespace :foreman do
  task :dev do
    `foreman start -f Procfile.dev`
  end
end

desc "Run Foreman using Procfile.dev"
task :foreman => 'foreman:dev'

/Users/me/.gem/ruby/2.0.0/gems/bundler-1.5.2/lib/bundler/rubygems_integration.rb:240:in `block in replace_gem': foreman is not part of the bundle. Add it to Gemfile. (Gem::LoadError)
    from /Users/me/.gem/ruby/2.0.0/bin/foreman:22:in `<main>'

Ruby users should take care not to install foreman in their project's Gemfile