Show quartiles of navigation timing data.
Start on a histogram for navigationTiming values.
Clean up the navigation timing chart with lots of extraction.

* It can take any number of series of data
* Width and height can be set in configuration.
Place top pages and top referrers on the same line.
Start to include support for tags.

* Tags are declared as a data-src attribute on the script.

```
   <script src="https://rum-diary.org/include.js" data-tags="exeriment,spdy"></script>
```
Add zopfli support
forgot to add grunt-zopfli to the dependencies
Fix zopfli not compressing the .min.js files.
Add the zopfli tag to stats.
Automatically redirect from http to https.
Only enable CORS headers for `POST /navigation`. Add more security headers

* Add HSTS, CSP, IEXSS, x-frame-options, x-content-type-options headers
* Add tests for the headers.
get rid of the headers when sending the /navigation request to avoid complicated CORS requests