Add csv gem as dependency.

refs gh-16

Gemfile

@@ -5,6 +5,8 @@ source 'http://rubygems.org'
 # Example:
 #   gem "activesupport", ">= 2.3.5"
 
+gem 'csv'
+
 # Add dependencies to develop your gem here.
 # Include everything needed to run rake, tests, features, etc.
 group :development, :test do

Gemfile.lock

@@ -3,6 +3,7 @@ GEM
   specs:
     allocation_stats (0.1.5)
     ast (2.4.2)
+    csv (3.3.0)
     json (2.7.2)
     language_server-protocol (3.17.0.3)
     minitest (5.25.1)
@@ -45,6 +46,7 @@ PLATFORMS
 
 DEPENDENCIES
   allocation_stats
+  csv
   minitest
   mocha
   rake

iso-639.gemspec

@@ -27,6 +27,7 @@ Gem::Specification.new do |s|
   ]
   s.homepage = 'http://github.com/xwmx/iso-639'
   s.require_paths = ['lib']
+  s.add_dependency9('csv')
   s.add_development_dependency('minitest',  '~> 5', '>= 0')
   s.add_development_dependency('mocha',     '~> 1', '>= 0')
   s.add_development_dependency('rdoc',      '~> 6', '>= 0')