Ensure page_route starts with a leading slash (#1604)

* Ensure page_route starts with a leading slash

* Handle base_url = nil in page_route()

* Refactor page_route()

lib/gollum/templates/navbar.mustache

@@ -2,7 +2,7 @@
 	
 	<div class="TableObject">
 		<div class="TableObject-item">
-	    <a class="btn" id="minibutton-home" href="{{page_route}}/">Home</a>
+	    <a class="btn" id="minibutton-home" href="{{page_route}}">Home</a>
 	  </div>
 
 

lib/gollum/views/helpers.rb

@@ -54,7 +54,7 @@ module Precious
       end
 
       def page_route(page = nil)
-        clean_url(@base_url, page)
+        clean_url("/#{@base_url}", page)
       end
 
       def clean_url(*url)