Fixing circular check crash

This removes the subscriber array in the ListenerMixin mixin since it's reference will
be reused among the components and break the circular reference check.
There were no tests in place for this and the comment made no sense to
why it was there.

This fixes #80

dist/reflux.js

@@ -370,11 +370,6 @@ var _ = _dereq_('./utils'),
  */
 module.exports = _.extend({
 
-    /**
-     * By adding this in the mixin we get error message if other React mixins try to use the same prop
-     */
-    subscriptions: [],
-
     /**
      * Cleans up all listener previously registered.
      */

src/ListenerMixin.js

@@ -7,11 +7,6 @@ var _ = require('./utils'),
  */
 module.exports = _.extend({
 
-    /**
-     * By adding this in the mixin we get error message if other React mixins try to use the same prop
-     */
-    subscriptions: [],
-
     /**
      * Cleans up all listener previously registered.
      */

test/usingListenerMixin.spec.js

@@ -37,6 +37,23 @@ describe('Managing subscriptions via ListenerMixin', function() {
         return assert.eventually.deepEqual(promise, [1337, 'ninja']);
     });
 
+    describe('using a store and listening to it', function() {
+        beforeEach(function () {
+            store = Reflux.createStore({
+                init: function() {
+                    this.listenTo(action, this.trigger);
+                }
+            });
+
+            component.listenTo(store, function() {});
+        });
+
+        it('should be possible to listen to the store using two different components', function() {
+            var component2 = Object.create(Reflux.ListenerMixin);
+            component2.listenTo(store, function() {});
+        });
+    });
+
     describe('get default data', function () {
         beforeEach(function() {
             component.componentWillUnmount();