remove alert mixin

js/mixins/alert_mixin.js

@@ -1,21 +0,0 @@
-'use strict';
-
-import React from 'react';
-import AlertDismissable from '../components/ascribe_forms/alert';
-
-let AlertMixin = {
-    setAlerts(errors){
-        let alerts = errors.map((error) => {
-            return <AlertDismissable error={error} key={error}/>;
-        });
-
-        this.setState({alerts: alerts});
-    },
-    
-    clearAlerts(){
-        this.setState({alerts: null});
-    }
-
-};
-
-export default AlertMixin;