support delimited keys like nconf

[mafar]

Please support nested keys like nconf. It is very useful

nconf https://github.com/indexzero/nconf

nconf.set('app:database:port', 5984);
// result
 {
   "app": {
     "database": {
      "port" : 5984
     }
   }
 }
nconf.set('app.database.port', 5984);
// result
{
  "app.database.port": 5984
}

It will be even better if delimited key is configurable at time of init like it could be : or , or whatever