don't prepend browser/ if known provider

src/config.js

@@ -33,7 +33,13 @@ function Config (storage) {
 
   this.ensureStorageUpdated = function (key) {
     if (key === 'currentFile') {
-      if (this.items[key] && this.items[key] !== '' && this.items[key].indexOf('browser/') !== 0 && this.items[key].indexOf('localhost/') !== 0) {
+      if (this.items[key] && this.items[key] !== '' &&
+        this.items[key].indexOf('browser/') !== 0 &&
+        this.items[key].indexOf('localhost/') !== 0 &&
+        this.items[key].indexOf('swarm/') !== 0 &&
+        this.items[key].indexOf('gist/') !== 0 &&
+        this.items[key].indexOf('github/') !== 0 &&
+        this.items[key].indexOf('ipfs/') !== 0) {
         this.items[key] = 'browser/' + this.items[key]
       }
     }