Lock down truncate_html version to 0.5.x.

Next version after 0.5.5 is 0.9 and it dropped Ruby 1.8.7 support but
we're still supporting it.

Author: ugisozols

Diff for: core/refinerycms-core.gemspec

@@ -25,7 +25,7 @@ Gem::Specification.new do |s|
   s.add_dependency 'railties',                    rails_version
   s.add_dependency 'activerecord',                rails_version
   s.add_dependency 'actionpack',                  rails_version
-  s.add_dependency 'truncate_html',               '~> 0.5'
+  s.add_dependency 'truncate_html',               '~> 0.5.5'
   s.add_dependency 'will_paginate',               '~> 3.0.2'
   s.add_dependency 'sass-rails',                  '~> 3.2.3'
   s.add_dependency 'jquery-rails',                '~> 2.0.0'