iOS 8 support.
Merge pull request #115 from xmartlabs/iOS8_support

iOS 8 support.
Swift compatibility fixes.
Merge branch 'master' of github.com:xmartlabs/XLForm into SwiftSupport
Merge pull request #116 from xmartlabs/SwiftSupport

Swift support
- Fixed XLFormImageSelectorCell KVO crash bug.
- Changed XLFormTextViewCell's value behavior so that an empty value equals nil (similar to XLFormTextFieldCell).
Merge pull request #118 from MuscleRumble/master

- Fixed XLFormImageSelectorCell KVO crash bug.
Fixed 'Expected a type' compiler error
Merge pull request #127 from robocopklaus/master

Fixed 'Expected a type' compiler error
Merge branch 'upstream-master'

* upstream-master:
  Fixed 'Expected a type' compiler error
  - Fixed XLFormImageSelectorCell KVO crash bug. - Changed XLFormTextViewCell's value behavior so that an empty value equals nil (similar to XLFormTextFieldCell).
  Swift compatibility fixes.
  iOS 8 support.