Rename HackMD view to CodiMD

Even when it looks a bit weird in first place to rename all internals
step by step, it makes sense to do so, because we run into confusion
afterwards.

Signed-off-by: Sheogorath <sheogorath@shivering-isles.com>

lib/response.js

@@ -119,7 +119,7 @@ function responseHackMD (res, note) {
     'Cache-Control': 'private', // only cache by client
     'X-Robots-Tag': 'noindex, nofollow' // prevent crawling
   })
-  res.render(config.hackmdPath, {
+  res.render(config.codimdPath, {
     url: config.serverURL,
     title: title,
     useCDN: config.useCDN,