Add development dependency on sqlite3 for running specs.

Author: tbsmatt

spec/spec_helper.rb

@@ -1,4 +1,4 @@
 $LOAD_PATH.unshift File.expand_path('../../lib', __FILE__)
 require 'value_objects'
 
-ActiveRecord::Base
+ActiveRecord::Base.establish_connection(adapter: 'sqlite3', database: ':memory:')

value_objects.gemspec

@@ -22,4 +22,5 @@ Gem::Specification.new do |s|
   s.add_development_dependency 'bundler', '~> 1.11'
   s.add_development_dependency 'rake', '~> 10.0'
   s.add_development_dependency 'rspec', '~> 3.0'
+  s.add_development_dependency 'sqlite3', '~> 1.3'
 end