Issue stephenou#58 : Update getPage() to have .slice(1)

Currently `getPage` returns `location.pathname.slice(-32)`
 This raises `slug` to not found when the pathname is longer

worker.js

@@ -219,7 +219,7 @@ class BodyRewriter {
         PAGE_TO_SLUG[page] = slug;
       });
       function getPage() {
-        return location.pathname.slice(-32);
+        return location.pathname.slice(1);
       }
       function getSlug() {
         return location.pathname.slice(1);