Revert "force certain options values for Firefox."

This reverts commit 11e781e6ac307ce9faf56a37c3ccca5ebefa5a33.

lib/dataconnection.js

@@ -14,12 +14,10 @@ function DataConnection(peer, dc, options) {
   this.open = false;
 
   this.label = options.label;
-  // Firefox is not this finely configurable.
   this.metadata = options.metadata;
-  this.serialization = util.browserisms !== 'Firefox' ? options.serialization : 'binary';
-  this._isReliable = util.browserisms !== 'Firefox' ? options.reliable : true;
-
+  this.serialization = options.serialization;
   this.peer = peer;
+  this._isReliable = options.reliable;
 
   this._dc = dc;
   if (!!this._dc) {