Update podspec github URL.
IOS-519
Version tags are in the form of "v1.5.0". Added the "v".
IOS-519
Made "Powered By Apptentive" logo hidden and unclickable if `showTagLine == NO`.
Fixes IOS-522
Fixed iOS 6 tint color issue in Surveys. 96536294503f8b1f18e585ba5bc87ea977199d18
Oops, wrong selector. e81531816774beed26e7f705771799ff480f2457
Fixes IOS-523
The `locale_language_code` is now based on `[[NSLocale preferredLanguages] firstObject]` rather than the `NSLocaleLanguageCode` locale component.
Fixes IOS-525
Fix for CocoaPod inheriting the spec's prefix header contents when evaluating a subspec.
https://github.com/CocoaPods/CocoaPods/issues/2211
Updated API changes doc for v1.5.1.
Updated Changelog
Updated version to 1.5.1
Fixed typo in `#if TARGET_OS_IPHONE`
`currentSystemVersion` was formerly reporting "Version 7.1.1 (Build 11D201)", now with the fix it reports "7.1.1".
Fixed issue with empty email address being saved as Person's email when sent from Engagement Rating Flow's Feedback Dialog.
CC https://github.com/apptentive/apptentive-ios/commit/70b80d56fbedd66d6ee47894ac19af3aadb9d4e5

Causes issue when saved into NSUserDefaults:
https://github.com/apptentive/apptentive-ios/commit/04062126dd04648f11b11f9d10f67671aa662a95#diff-92924b5b3b8a9efa9bef7cae889827cbR155
cleanup
Email is set to `[NSNull null]` in `apiJSON` to delete email from server. But `[NSNull null]` crashes if saved in NSUserDefaults.
Changed ATPersonUpdater to save a version of the person `apiJSON` that does not contain `[NSNull null` email.
Fixes IOS-526
Merge pull request #99 from apptentive/Next

Fix for saving `[NSNull null]` email to NSUserDefaults
Version 1.5.2 update.
Fixed issue where `ask_for_email` feature was always set to YES.
Clean up logging of events and available interactions.
Fixes IOS-521
Merge pull request #102 from apptentive/dev

Clean up logging of events and available interactions.
"Require Email" not respected by Feedback Dialog in engagement rating prompt.
Fixes IOS-530