Allow whitelisting of individual webpage - Phase 2

Background / User story

As ABP User I would like to whitelist individual webpage only so I don't need to do it for the entire domain. See #3 (closed) for phase 1.

What to change

• Design: https://eyeogmbh.invisionapp.com/share/TYSWLRTQ37D
• Research: None.
• Spec: eyeo/specs/spec!247
• Development:
  • Individual webpage whitelisting
  • Use the new refresh content

Hints for testers

None.

Hints for translators

• Added strings:
  • refresh_this_page
  • status_domain
  • status_page
• Updated strings:
  • refresh_to_take_effect
  • status_header

Integration notes

We are now using the singlePage flag in the "filters.whitelist" and "filters.unwhitelist" messages. Whenever that flag is true, instead of whitelisting the given website, only the given web page should be whitelisted (see also webext#77).