title: Sencha Touch 2.2 icons not displaying with Base theme
body: <p>I'm trying to make my own custom theme, for this I import the Base theme.</p>
  
  <p>I'm trying to add icons to buttons like this :</p>
  
  <pre><code>{
      xtype: 'button',
      align : 'left',
      name : 'btnName',
      iconCls : 'team',
      iconMask: 'true'
  }
  </code></pre>
  
  <p>The icon isn't showing, but if I use the default theme they are. And I already set the variable $include-default-icons to true.</p>
  
  <p>My custom button: </p>
  
  <pre><code>@mixin modus-button($color) {
      @include transition(all .25s ease);
      @include border-radius(6px);
      margin-bottom: 15px;
      font-size: 15px;
      background: $color;
      border: none;
      color: white;
      text-decoration: none;
  
      .x-button-label {
          padding: 10px 0;
      }
  
      &amp;.x-button-pressing {
          background: darken($color, 10);
      } 
  
      // Default icon style
      .x-button-icon {
          width: 1.5em;
          height: 1.5em;
  
          &amp;:before {
              font-size: 1.6em;
              line-height: 1em;
          }
      }
  }
  </code></pre>
  
  <p>What should I add to display icons with base theme ? </p>