Bug 27476: Implement about:torconnect captive portal within Tor Browser

- implements new about:torconnect page as tor-launcher replacement
- adds tor connection status to url bar and tweaks UX when not online
- adds new torconnect component to browser
- tor process management functionality remains implemented in tor-launcher through the TorProtocolService module
- adds warning/error box to about:preferences#tor when not connected to tor
- explicitly allows about:torconnect URIs to ignore Resist Fingerprinting (RFP)
- various tweaks to info-pages.inc.css for about:torconnect (also affects other firefox info pages)

Bug 40773: Update the about:torconnect frontend page to match additional UI flows