title: Angular ng2-file-upload Input File Filter not working for PNG in Internet Explorer
body: <p>I am using the file uploader from ng2-file-upload with filetype restriction.
  However everytime i choose a png file with the Internet Explorer 11, it is not added into the queue. All the other allowed filetypes are working. 
  Here is the code with the file Options:</p>
  
  <p><div class="snippet" data-lang="js" data-hide="false" data-console="true" data-babel="false">
  <div class="snippet-code">
  <pre class="snippet-code-js lang-js prettyprint-override"><code>let uploadOptions: FileUploaderOptions;
  if (navigator.userAgent.match(/Trident.*rv\:11\./)) {
    uploadOptions = {
      url: uploadUrl,
      allowedFileType: ['xls', 'xlsx', 'doc', 'docx', 'pdf', 'gif', 'jpg', 'jpeg', 'png', 'odt', 'txt', 'ods'],
      maxFileSize: 10 * 1024 * 1024
    };
  } else {
    uploadOptions = {
      url: uploadUrl,
      allowedMimeType: ['application/pdf',
        'application/vnd.ms-excel',
        'application/vnd.openxmlformats-officedocument.spreadsheetml.sheet',
        'application/msword',
        'application/vnd.openxmlformats-officedocument.wordprocessingml.document',
        'application/vnd.oasis.opendocument.text',
        'application/vnd.oasis.opendocument.spreadsheet',
        'image/gif',
        'image/jpeg',
        'image/png'
      ],
      maxFileSize: 10 * 1024 * 1024
    };
  
  }
  
  this.uploader = new FileUploader(uploadOptions);
  this.uploader.onCompleteAll = () =&gt; {
    this.editStateService.documentAdded('player', 'document');
    this.documentListUpdated.emit();
    this.uploader.clearQueue();
  };</code></pre>
  </div>
  </div>
  </p>
  
  <p>Anybody know how to get this working?</p>