title: Convert Promise to Observable
body: <p>I am trying to wrap my head around observables. I love the way observables solve development and readability issues. As I read, benefits are immense. </p>
  
  <p>Observables on HTTP and collections seem to be straight forward. How can I convert something like this to observable pattern.</p>
  
  <p>This is from my service component, to provide authentication. I'd prefer this to work like other HTTP services in Angular2 - with support for data, error and completion handlers.</p>
  
  <pre class="lang-js prettyprint-override"><code>firebase.auth().createUserWithEmailAndPassword(email, password)
    .then(function(firebaseUser) {
      // do something to update your UI component
      // pass user object to UI component
    })
    .catch(function(error) {
      // Handle Errors here.
      var errorCode = error.code;
      var errorMessage = error.message;
      // ...
    });
  </code></pre>
  
  <p>Any help here would be much appreciated. The only alternative solution I had was to create <code>EventEmitter</code>s. But I guess that's a terrible way to do things in services section</p>