Reset icon after forward/backward navigation inside tab.

v0.5:
* Now keeps track of all the domains served by Cloudflare. The detection icon now changes color according to:
- no requests served by Cloudflare = green
- only external resources served by Cloudflare = orange
- page itself (or resources from same domain) served by Cloudflare = red
* Details about the detected Cloudflare requests are available by clicking on the detection icon.
* New icons.
* Bugfix: First request is no longer lost (e.g. archive.is is now properly detected again).

v0.6:
* Make popup work in private mode.

v0.6.1:
* Dummy increase in version number.

v0.3:
Reset indicator icon/title when tab URL changes.

v0.2:
Fix for Firefox 52: Ignore case when matching headers.