title: Add components to Vue instance after instance is created
body: <p>If you've created a VueJS instance like this...</p>
  
  <p>var app = new Vue({
    el: '#app',
    components: {...}
  })</p>
  
  <p>Is it possible to add components to this instance it's instantiated?</p>
  
  <p>The reason I ask is that we have a multi-page app which stares a template. We want the instantiation of the Vue app to be in the shared template code but we want each page to use different components so for example the code on the contact page would be split between two files...</p>
  
  <p><strong>Master.js</strong>
  <strong>Contact.js</strong></p>
  
  <p>The contact.js file would need to tell the main app that it wanted to use the conract-form component, but that component is not used on other pages so we don't want to add it to the initial app declaration in the master.js </p>
  
  <p>Any help would really be appreciated.</p>