Added `hide_branding` remote config and `initiallyHideBranding` API property.
This replaces the local `showTagLine` API property of ATConnect.
IOS-532
Use `hideBranding` in places that formerly used `showTagLine`.
IOS-532
Add `hideBranding` check to Upgrade Messages.
IOS-532
Pointer.
Merge pull request #105 from apptentive/hideBranding

Hide Apptentive Branding remote configuration option.