static generateTabHeaderTemplate(tabId, tabName, filename) {    
    let tabMarkup = (filename === undefined) ? 
      `<a href="#tab-${tabId}">${ tabId + " [no name]"}</a>` :
      `<a href="#tab-${tabId}" title="${filename}">${ tabName }</a>` 
    return `
      <li data-tab="${tabId}">
        ${ tabMarkup }
        <span class="ui-icon ui-icon-close" role="presentation">Remove Tab</span>
      </li>
    `
  }
Creates tab html

@param {Integer} tabId