title: ngx-gallery only showing medium size images
body: <p>I´ve build an image gallery using angular ngx-gallery. I cant get the responsive to work since the small and big images doesnt show. It only displays the medium 
   size images. </p>
  
  <p>Here is how I implemented it:</p>
  
  <p>These are the options:</p>
  
  <pre><code>this.galleryOptions = [
          {
              width: '100%',
              height: '254px',
              imageAutoPlay: true,
              imageAutoPlayPauseOnHover: true,
              imageSize: NgxGalleryImageSize.Contain,
              imageAnimation: NgxGalleryAnimation.Slide,
              thumbnails: false,
              preview: false
          },
          // max-width 544
          {
              breakpoint: 544,
              width: '100%',
              height: '250px',
              imageSwipe: true,
              imageArrowsAutoHide:true,
              imageAutoPlay: true,
              imageAutoPlayPauseOnHover: true,
              imageSize: NgxGalleryImageSize.Cover,
              imageAnimation: NgxGalleryAnimation.Slide,
              thumbnails: false,
              preview: false
          }
      ]; 
  </code></pre>
  
  <p>This is the array of images: (all url checked)</p>
  
  <pre><code>    this.galleryImages = [
          {
              small: 'assets/images/BannersResponsive/culturizate.jpg',
              medium: 'assets/images/Banners/radio_online_venezuela_fondo_demananacontigo.png',
              big: 'assets/images/BannersResponsive/culturizate.jpg'
          },
          {
              small: 'assets/images/BannersResponsive/culturizate.jpg',
              medium: 'assets/images/Banners/radio_online_venezuela_fondo_conexionyreflexion.png',
              big: 'assets/images/Banners/radio_online_venezuela_fondo_conexionyreflexion.png'
          }, ];
  </code></pre>
  
  <p>and this is the html:</p>
  
  <pre><code>&lt;ngx-gallery class="gallery"                        
    [options]="galleryOptions                         
    [images]="galleryImages"&gt;&lt;/ngx-gallery&gt;    
  </code></pre>
  
  <p>I also tried naming the images the same and putting small,medium and big at the end of the name.</p>
  
  <p>Thank you in advance.</p>