Handle Config changes via UI - MessageCampaigns fix

https://trello.com/c/R4XrYTJA

This commit refactors SettingsController for Message Campaigns module.
The class does no longer use platformSettingsService to read and register
its settings, but instead does it via SettingsFacade.

Change-Id: Ie3d6717fbb690d50041c2d4e2f0a7597a6b9cee4
Merge "Handle Config changes via UI - MessageCampaigns fix"