Add base64 as a runtime dependency

Author: orien

webmachine.gemspec

@@ -27,6 +27,7 @@ Gem::Specification.new do |gem|
   gem.add_runtime_dependency('i18n', ['>= 0.4.0'])
   gem.add_runtime_dependency('multi_json')
   gem.add_runtime_dependency('as-notifications', ['>= 1.0.2', '< 2.0'])
+  gem.add_runtime_dependency('base64')
 
   gem.add_development_dependency('webrick', ['~> 1.7.0'])
   gem.add_development_dependency('standard', ['~> 1.21'])