WIP: add whitelist

[smichel17]

• [x] Split package structure changes and functional changes into separate commits.
• [x] Decide whether to whitelist per-app, per-activity, or both (or offer a setting)
  • Let's start with what we've got and change it if there's a need later.
• [x] Improve strings
  • [x] Notification actions Whitelist and Un-whitelist are pretty inscrutable
    • Maybe we could put explanatory text in the notification body, or add an intro screen?
    • Exclude app, Pause in excluded apps, Don't exclude
  • [x] Update subscreen longer description to reflect new functionality.
  • [x] Update subscreen title to Pause in whitelisted apps
• [x] Testing on my own device for a while to find bugs.
  • apk: http://smichel.me/files/red-moon/red-moon-debug-2017-09-21-9fe4126_monitoring.apk

[smichel17]

Okay, so it wasn't actually easy to break this apart into bits. The only part I could have feasibly done was moving the single file, CurrentAppMonitor.kt, and that's a minor enough change that meh, not worth it.

[smichel17]

@joonatoona Actually, this isn't quite ready to merge, I want to update the strings first.

[smichel17]

@joonatoona Okay, ready to merge when you'd like.