Remove pdf export code

Signed-off-by: Tilman Vatteroth <tilman.vatteroth@tu-dortmund.de>

app.js

@@ -191,7 +191,6 @@ app.locals.serverURL = config.serverURL
 app.locals.sourceURL = config.sourceURL
 app.locals.allowAnonymous = config.allowAnonymous
 app.locals.allowAnonymousEdits = config.allowAnonymousEdits
-app.locals.allowPDFExport = config.allowPDFExport
 app.locals.authProviders = {
   facebook: config.isFacebookEnable,
   twitter: config.isTwitterEnable,