Give github-markup gem a version requirement

Gemfile

@@ -44,8 +44,8 @@ gem "ffaker"
 gem "seed-fu"
 
 # Markdown to HTML
-gem "redcarpet", "~> 2.1.1"
-gem 'github-markup'
+gem "redcarpet",     "~> 2.1.1"
+gem "github-markup", "~> 0.7.4"
 
 # Servers
 gem "thin"

Gemfile.lock

@@ -397,7 +397,7 @@ DEPENDENCIES
   ffaker
   foreman
   git
-  github-markup
+  github-markup (~> 0.7.4)
   gitlab_meta (= 2.9)
   gitolite!
   grack!