Fixes IOS-187 Entering text in one free form field overrides another free form field's data

If the text field didn't have an answer associated with it, but was being reused, the text wasn't being overriden.
Merge branch 'Next' of github.com:apptentive/apptentive-ios into Next
 - Added alternative methods to open App Store
Added metrics for opening app via StoreKit vs. URL
Small additions for IOS-233 and an update to the changelog.
Merge branch 'master' into Next
Add `distribution_version` to API
Fixes IOS-234
References APPTENTIVE-1484
Changed version number to 1.2.1
Adding distribution and distribution_version where they should've actually been.