Add OS build string to device info.
iOS 8.0.2  > build "12A405".
Fixes IOS-654
Safer construction of `device` dictionary, in case any of these methods return `nil` in a future OS update.
Methods for combining vendor, interaction, and event into a codepoint.
Added `willShowInteractionForEvent:` method for determining if an interaction will be shown the next time you engage the given event.
Fixes IOS-512
Fixes #116
Tests for `willShowInteractionForEvent:`
Move photo selection from `clickedButtonAtIndex:` to `didDismissWithButtonIndex:` to fix iOS 8 iPad photo selection issue.
 > Warning: Attempt to present <UIImagePickerController>  on <ATSimpleImageViewController> which is already presenting (null)
http://stackoverflow.com/questions/24942282/uiimagepickercontroller-not-presenting-in-ios-8
Fixes IOS-661
Merge branch 'willShowInteraction' into Next
Modified `willShowInteractionForEvent:` description.
#132
Renamed `engage:(NSString *)...` parameter name from `eventLabel` to `event`.
Fixes IOS-658
Fixing various static analyzer warnings in Xcode 6.0.1.
Merge pull request #133 from wooster/Next

Fixing various static analyzer warnings in Xcode 6.0.1.
Added a xib-based Launch Screen.
Moved the events engaged in FeedbackDemo to `defines.h`.
Easier customization of events in FeedbackDemo.
Merge pull request #138 from apptentive/xibLaunchScreen

Added a xib-based Launch Screen.
Converted FeedbackDemo app icons and launch images to Asset Catalogs.
Fixes Xcode warning where pre-7.1 devices cannot use xib-based launch images.
Set Launch Image for iOS 7,8 Retina 4 in Asset Catalog.
Fixes Xcode warning: "An iPhone Retina (4-inch) launch image for iOS 7.0 and later is required."
Update to v1.6.0