Update markdown-it

closes #6626

Gemfile

@@ -93,7 +93,7 @@ gem "js-routes",         "1.2.0"
 source "https://rails-assets.org" do
   gem "rails-assets-jquery",                              "1.11.2" # Should be kept in sync with jquery-rails
 
-  gem "rails-assets-markdown-it",                         "5.0.2"
+  gem "rails-assets-markdown-it",                         "5.1.0"
   gem "rails-assets-markdown-it-hashtag",                 "0.4.0"
   gem "rails-assets-markdown-it-diaspora-mention",        "0.4.0"
   gem "rails-assets-markdown-it-sanitizer",               "0.4.1"

Gemfile.lock

@@ -565,7 +565,7 @@ GEM
     rails-assets-jquery.ui (1.11.4)
       rails-assets-jquery (>= 1.6)
     rails-assets-markdown-it--markdown-it-for-inline (0.1.1)
-    rails-assets-markdown-it (5.0.2)
+    rails-assets-markdown-it (5.1.0)
     rails-assets-markdown-it-diaspora-mention (0.4.0)
     rails-assets-markdown-it-hashtag (0.4.0)
     rails-assets-markdown-it-sanitizer (0.4.1)
@@ -856,7 +856,7 @@ DEPENDENCIES
   rails-assets-jquery (= 1.11.2)!
   rails-assets-jquery-placeholder (= 2.3.1)!
   rails-assets-jquery-textchange (= 0.2.3)!
-  rails-assets-markdown-it (= 5.0.2)!
+  rails-assets-markdown-it (= 5.1.0)!
   rails-assets-markdown-it--markdown-it-for-inline (= 0.1.1)!
   rails-assets-markdown-it-diaspora-mention (= 0.4.0)!
   rails-assets-markdown-it-hashtag (= 0.4.0)!