remove applySettings hook and allow credentials.json to be part of core

.gitignore

@@ -17,3 +17,4 @@ npm-debug.log
 *.crt
 *.key
 bin/etherpad-1.deb
+credentials.json

settings.json.template

@@ -2,6 +2,9 @@
   This file must be valid JSON. But comments are allowed
 
   Please edit settings.json, not settings.json.template
+
+  To still commit settings without credentials you can 
+  store any credential settings in credentials.json
 */
 {
   // Name your instance!