Surveys Controller for interaction-based surveys
IOS-463
Boilerplate for showing Survey interactions.
Fixes IOS-463
Adding ability to query Device and Person information in Interaction criteria.
Device: "device/hardware" = "x86_64"
Person: "person/name" = "Peter"
Need to be tested with final device/person criteria from server.
Fixes IOS-467 and IOS-468
Create and show a survey from an interaction.
IOS-476
Added sample survey interaction to engagement manifest.
Modified Feedback Demo to show Survey Interaction.
Method to engage Apptentive events with userInfo dictionary.
Engage the Survey internal events "launch", "send", and "cancel".
IOS-475
Added Survey migration directions to the Engagement Framework migration document.
IOS-473.
Removed debug code that added test Survey to interaction manifest.
Merge branch 'Next' into engagementSurveys

Conflicts:
	ApptentiveConnect/source/Engagement/Persistence/ATEngagementBackend.h
Merge branch 'Next' into engagementSurveys
Updated Feedback Demo for Engagement Framework Surveys.
Can engage events "showSurvey" and "presentSurvey"
Removed ATSurveys.h/m
IOS-483
Surveys have moved to the Engagement framework; remove dedicated Survey retrieval code.
IOS-483
Removed `availableSurveys`
Removed legacy Survey presenting code
Removed currentSurvey
Removed `hasSurveyAvailable` methods
Moved strings to ATSurveyViewController
Removing more legacy code from ATBackend