title: bootstrap input field and input-addon not on the same line
body: <p>Does anybody can explain me why input-group-addon stay above input field?</p>
  
  <p><strong>HTML</strong></p>
  
  <pre><code>   &lt;div class="container"&gt;
    &lt;div class="row"&gt;
      &lt;div class="center"&gt;
        &lt;form class="form-horizontal" id="formLogin"&gt;
          &lt;div class="form-group"&gt;
            &lt;span class="input-group-addon"&gt;&lt;i class="fa fa-at"&gt;&lt;/i&gt;&lt;/span&gt;
            &lt;input type="email" class="form-control" id="inputEmail" placeholder="Email"&gt;
          &lt;/div&gt;
          &lt;div class="form-group"&gt;
            &lt;span class="input-group-addon"&gt;&lt;i class="fa fa-lock"&gt;&lt;/i&gt;&lt;/span&gt;
            &lt;input type="password" class="form-control" id="inputPassword" placeholder="Password"&gt;
          &lt;/div&gt;
          &lt;div class="form-group"&gt;
            &lt;input type="submit" class="btn btn-primary btn-block" value="Login"&gt;
            &lt;a href="#" class="btn btn-default btn-block" id="linkRegister"&gt;SignUp&lt;/a&gt;
          &lt;/div&gt;
      &lt;/div&gt;
    &lt;/div&gt;
    &lt;/form&gt;
  </code></pre>
  
  <p><strong>CSS</strong></p>
  
  <pre><code>.center {
      width: 50%;
      height: 50%;
      margin: auto;
      min-width: 225px;
      max-width: 275px;
      position: relative;
      top: 180px;
  }
  </code></pre>
  
  <p>Example <a href="http://codepen.io/anon/pen/BNoqWZ" rel="nofollow">http://codepen.io/anon/pen/BNoqWZ</a></p>
  
  <p>Thanks.</p>