contrib: add Admin page to update contributor status. Start migrating from User.backer => User.contributor

src/models/user.js

@@ -54,12 +54,18 @@ var UserSchema = new Schema({
 
   backer: {
     tier: Number,
-    admin: Boolean,
+    //admin: Boolean, // FIXME migrate to contributor.admin
     npc: String,
-    contributor: String,
+    //contributor: String, // FIXME migrate to contributor.text
     tokensApplied: Boolean
   },
 
+  contributor: {
+    level: Number, // 1-7, see https://trello.com/c/wkFzONhE/277-contributor-gear
+    admin: Boolean,
+    text: String, // Artisan, Friend, Blacksmith, etc
+  },
+
   balance: Number,
   filters: {type: Schema.Types.Mixed, 'default': {}},