Abstract all file-system operations

Stage 1 of  #62

settings.js

@@ -16,6 +16,8 @@
 module.exports = {
     uiPort: 1880,
     
+    userDir: "/tmp/a",
+    
     // By default, the Node-RED UI accepts connections on all IPv4 interfaces.
     // The following property can be used to listen on a specific interface. For
     // example, the following would only allow connections from the local machine. 
@@ -28,6 +30,10 @@ module.exports = {
     // The file containing the flows. If not set, it defaults to flows_<hostname>.json
     //flowFile: 'flows.json',
     
+    // By default, all user data is stored in the Node-RED install directory. To
+    // use a different location, the following property can be used
+    //userDir: '/home/nol/.node-red/',
+    
     // You can protect the user interface with a userid and password by using the following property
     // the password must be an md5 hash  eg.. 5f4dcc3b5aa765d61d8327deb882cf99 ('password')
     //httpAuth: {user:"user",pass:"5f4dcc3b5aa765d61d8327deb882cf99"},