Add option to disable livepreview from settings

lib/gollum/frontend/app.rb

@@ -76,7 +76,7 @@ module Precious
       @name = params[:splat].first
       wiki = Gollum::Wiki.new(settings.gollum_path, settings.wiki_options)
       if page = wiki.page(@name)
-        if page.format.to_s.include?('markdown') && supported_useragent?(request.user_agent)
+        if settings.wiki_options[:live_preview] && page.format.to_s.include?('markdown') && supported_useragent?(request.user_agent)
           redirect '/livepreview/index.html?page=' + encodeURIComponent(@name)
         else
           @page = page

lib/gollum/wiki.rb

@@ -139,6 +139,7 @@ module Gollum
     #           site.
     # options - Optional Hash:
     #           :universal_toc - Table of contents on all pages.  Default: false
+    #           :live_preview  - Livepreview editing for markdown files. Default: true
     #           :base_path     - String base path for all Wiki links.
     #                            Default: "/"
     #           :page_class    - The page Class. Default: Gollum::Page
@@ -173,6 +174,7 @@ module Gollum
         self.class.default_ws_subs
       @history_sanitization = options[:history_sanitization] ||
         self.class.history_sanitization
+      @live_preview  = options.fetch(:live_preview, true)
       @universal_toc = options.fetch(:universal_toc, false)
       @mathjax = options[:mathjax] || true
     end