Add NodeGirls Mob Programming photo (#56)

Author: rodolfoprr

slides/index.html

@@ -74,14 +74,9 @@ <h1 class="try">Principles and Rules</h1>
   <section id="formats">
 
     <article>
-      <h1 class="try">Formats</h1>
-      <p style="float: left; margin-right: 10px">
-        Randori<br />
-        <img src="https://c1.staticflickr.com/4/3660/3485959503_acdc40c696.jpg" width="400" />
-      </p>
+      <h1 class="try">Mob Programming</h1>
       <p>
-        &nbsp;&nbsp; Mob Programming<br />
-         <img src="https://cloud.githubusercontent.com/assets/2061821/23492131/b4427b72-ff56-11e6-8944-7efcec4f9787.jpg" width="400" />
+         <img src="https://secure.meetupstatic.com/photos/event/9/3/6/a/highres_469477738.jpeg" width="700" />
       </p>
     </article>
 
@@ -127,7 +122,6 @@ <h1 class="try">Red-Green-Refactor</h1>
 
   </section>
 
-
   <section id="show-me-the-code">
 
     <article>