Updates Redcarpet (Markdown parser) to 3.4.0

Adds suppport for HTML 5 details and summary tags (https://github.com/vmg/redcarpet/issues/578)

Gemfile

@@ -105,7 +105,7 @@ gem 'seed-fu', '~> 2.3.5'
 gem 'html-pipeline',        '~> 1.11.0'
 gem 'deckar01-task_list',   '1.0.6', require: 'task_list/railtie'
 gem 'gitlab-markup',        '~> 1.5.1'
-gem 'redcarpet',            '~> 3.3.3'
+gem 'redcarpet',            '~> 3.4'
 gem 'RedCloth',             '~> 4.3.2'
 gem 'rdoc',                 '~> 4.2'
 gem 'org-ruby',             '~> 0.9.12'

Gemfile.lock

@@ -583,7 +583,7 @@ GEM
     recaptcha (3.0.0)
       json
     recursive-open-struct (1.0.0)
-    redcarpet (3.3.3)
+    redcarpet (3.4.0)
     redis (3.2.2)
     redis-actionpack (5.0.1)
       actionpack (>= 4.0, < 6)
@@ -955,7 +955,7 @@ DEPENDENCIES
   rblineprof (~> 0.3.6)
   rdoc (~> 4.2)
   recaptcha (~> 3.0)
-  redcarpet (~> 3.3.3)
+  redcarpet (~> 3.4)
   redis (~> 3.2)
   redis-namespace (~> 1.5.2)
   redis-rails (~> 5.0.1)