Adding site map generation #185

using the sitemap_generator gem, trigger daily by clock, generated in a sidekiq worker
Some example output
```
This XML file does not appear to have any style information associated with it. The document tree is shown below.
<urlset xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://www.sitemaps.org/schemas/sitemap/0.9" xmlns:image="http://www.google.com/schemas/sitemap-image/1.1" xmlns:video="http://www.google.com/schemas/sitemap-video/1.1" xmlns:geo="http://www.google.com/geo/schemas/sitemap/1.0" xmlns:news="http://www.google.com/schemas/sitemap-news/0.9" xmlns:mobile="http://www.google.com/schemas/sitemap-mobile/1.0" xmlns:pagemap="http://www.google.com/schemas/sitemap-pagemap/1.0" xmlns:xhtml="http://www.w3.org/1999/xhtml" xsi:schemaLocation="http://www.sitemaps.org/schemas/sitemap/0.9 http://www.sitemaps.org/schemas/sitemap/0.9/sitemap.xsd">
<url>
<loc>https://test.com</loc>
<lastmod>2014-09-25T16:53:37+00:00</lastmod>
<changefreq>always</changefreq>
<priority>1.0</priority>
</url>
<url>
<loc>https://test.com/welcome</loc>
<lastmod>2014-09-25T16:53:37+00:00</lastmod>
<changefreq>montlhy</changefreq>
<priority>0.7</priority>
</url>
<url>
<loc>https://test.com/contact_us</loc>
<lastmod>2014-09-25T16:53:37+00:00</lastmod>
<changefreq>montlhy</changefreq>
<priority>0.5</priority>
</url>
<url>
<loc>https://test.com/blog</loc>
<lastmod>2014-09-25T16:53:37+00:00</lastmod>
<changefreq>weekly</changefreq>
<priority>0.7</priority>
</url>
<url>
<loc>https://test.com/api</loc>
<lastmod>2014-09-25T16:53:37+00:00</lastmod>
<changefreq>monthly</changefreq>
<priority>0.5</priority>
</url>
<url>
<loc>https://test.com/faq</loc>
<lastmod>2014-09-25T16:53:37+00:00</lastmod>
<changefreq>monthly</changefreq>
<priority>0.5</priority>
</url>
<url>
<loc>https://test.com/privacy_policy</loc>
<lastmod>2014-09-25T16:53:37+00:00</lastmod>
<changefreq>monthly</changefreq>
<priority>0.2</priority>
</url>
<url>
<loc>https://test.com/tos</loc>
<lastmod>2014-09-25T16:53:37+00:00</lastmod>
<changefreq>monthly</changefreq>
<priority>0.2</priority>
</url>
<url>
<loc>https://test.com/jobs</loc>
<lastmod>2014-09-25T16:53:37+00:00</lastmod>
<changefreq>daily</changefreq>
<priority>0.7</priority>
</url>
<url>
<loc>https://test.com/employers</loc>
<lastmod>2014-09-25T16:53:37+00:00</lastmod>
<changefreq>monthly</changefreq>
<priority>0.7</priority>
</url>
<url>
<loc>https://test.com/p/lwl_wq</loc>
<lastmod>2014-09-25T02:34:32+00:00</lastmod>
<changefreq>weekly</changefreq>
<priority>0.5</priority>
</url>
<url>
<loc>https://test.com/p/yug7ha</loc>
<lastmod>2014-09-25T02:34:33+00:00</lastmod>
<changefreq>weekly</changefreq>
<priority>0.5</priority>
</url>
<url>
<loc>https://test.com/p/-xrl3q</loc>
<lastmod>2014-09-25T02:34:33+00:00</lastmod>
<changefreq>weekly</changefreq>
<priority>0.5</priority>
</url>
<url>
<loc>https://test.com/team/put-a-bird-on-it</loc>
<lastmod>2014-09-25T02:34:34+00:00</lastmod>
<changefreq>weekly</changefreq>
<priority>0.5</priority>
</url>
<url>
<loc>https://test.com/team/team-awesome</loc>
<lastmod>2014-09-25T02:00:30+00:00</lastmod>
<changefreq>weekly</changefreq>
<priority>0.5</priority>
</url>
<url>
<loc>https://test.com/team/team-wonderful</loc>
<lastmod>2014-09-25T02:28:58+00:00</lastmod>
<changefreq>weekly</changefreq>
<priority>0.5</priority>
</url>
<url>
<loc>https://test.com/team/parker-dibbert</loc>
<lastmod>2014-09-25T02:31:33+00:00</lastmod>
<changefreq>weekly</changefreq>
<priority>0.5</priority>
</url>
<url>
<loc>https://test.com/team/glamouros</loc>
<lastmod>2014-09-25T02:52:01+00:00</lastmod>
<changefreq>weekly</changefreq>
<priority>0.5</priority>
</url>
<url>
<loc>
https://test.com/team/glamouros/Manger-of-Cool-wrfhdg
</loc>
<lastmod>2014-09-25T02:52:01+00:00</lastmod>
<changefreq>weekly</changefreq>
<priority>0.5</priority>
</url>
<url>
<loc>https://test.com/bryce</loc>
<lastmod>2014-09-25T02:34:34+00:00</lastmod>
<changefreq>weekly</changefreq>
<priority>0.5</priority>
</url>
<url>
<loc>https://test.com/lisa</loc>
<lastmod>2014-09-25T02:34:34+00:00</lastmod>
<changefreq>weekly</changefreq>
<priority>0.5</priority>
</url>
<url>
<loc>https://test.com/testser</loc>
<lastmod>2014-09-25T04:52:54+00:00</lastmod>
<changefreq>weekly</changefreq>
<priority>0.5</priority>
</url>
<url>
<loc>https://test.com/blog/2012-02-23-hating-on-IE6</loc>
<lastmod>2012-02-23T21:37:05-08:00</lastmod>
<changefreq>weekly</changefreq>
<priority>0.5</priority>
</url>
<url>
<loc>
https://test.com/blog/2012-02-05-the-companies-id-want-to-work-for
</loc>
<lastmod>2012-02-05T20:55:47-08:00</lastmod>
<changefreq>weekly</changefreq>
<priority>0.5</priority>
</url>
<url>
<loc>
https://test.com/blog/2012-01-16-the-hacker-version-of-an-embeddable-social-button
</loc>
<lastmod>2012-01-16T11:02:41-08:00</lastmod>
<changefreq>weekly</changefreq>
<priority>0.5</priority>
</url>
<url>
<loc>
https://test.com/blog/2012-01-10-represent-get-geek-cred-on-your-blog
</loc>
<lastmod>2012-01-10T12:04:36-08:00</lastmod>
<changefreq>weekly</changefreq>
<priority>0.5</priority>
</url>
<url>
<loc>
https://test.com/blog/2012-01-09-starting-off-the-new-year-with-a-bang
</loc>
<lastmod>2012-01-09T14:25:31-08:00</lastmod>
<changefreq>weekly</changefreq>
<priority>0.5</priority>
</url>
<url>
<loc>https://test.com/blog/2011-07-22-gaming-the-game</loc>
<lastmod>2011-07-22T00:09:00-08:00</lastmod>
<changefreq>weekly</changefreq>
<priority>0.5</priority>
</url>
</urlset>
```
I see. Then fine, let keep it. I didn't know that heroku is RO.