fix: copytime throws error on includeTimeline variable

[joemidi]

events.js:163
      throw er; // Unhandled 'error' event
      ^

ReferenceError: /Users/joepadas/Sites/generator-bannertime/generators/app/templates/src/300x250/_index.html:14
    12|     <script src="js/banner.js" type="text/javascript"></script>
    13|     <script src="js/banner.loader.js" type="text/javascript"></script>
 >> 14|     <script src="js/banner.animation.js" type="text/javascript"></script><% if (includeTimeline) { %>
    15|     <!--removeIf(production)-->
    16|     <script src="https://s3-us-west-2.amazonaws.com/s.cdpn.io/35984/ScrubGSAPTimeline.js" type="text/javascript"></script>
    17|     <!--endRemoveIf(production)--><% } %>

includeTimeline is not defined
    at eval (eval at compile (/Users/joepadas/Sites/generator-bannertime/node_modules/ejs/lib/ejs.js:481:12), <anonymous>:36:12)
    at returnedFn (/Users/joepadas/Sites/generator-bannertime/node_modules/ejs/lib/ejs.js:512:17)
    at Object.exports.render (/Users/joepadas/Sites/generator-bannertime/node_modules/ejs/lib/ejs.js:316:37)
    at process (/Users/joepadas/Sites/generator-bannertime/node_modules/mem-fs-editor/lib/actions/copy-tpl.js:12:18)
    at applyProcessingFunc (/Users/joepadas/Sites/generator-bannertime/node_modules/mem-fs-editor/lib/actions/copy.js:13:16)
    at EditionInterface.exports._copySingle (/Users/joepadas/Sites/generator-bannertime/node_modules/mem-fs-editor/lib/actions/copy.js:63:16)
    at files.forEach.file (/Users/joepadas/Sites/generator-bannertime/node_modules/mem-fs-editor/lib/actions/copy.js:50:10)
    at Array.forEach (native)
    at EditionInterface.exports.copy (/Users/joepadas/Sites/generator-bannertime/node_modules/mem-fs-editor/lib/actions/copy.js:49:9)
    at EditionInterface.module.exports [as copyTpl] (/Users/joepadas/Sites/generator-bannertime/node_modules/mem-fs-editor/lib/actions/copy-tpl.js:10:8)