Provide QKAttribute, an Objective-C version of Attribute

This is mostly compatible with KFAttribute from KFData
Remove designated initializers from Objective-C

These don't work in Xcode 5
[Podspec] Include Objective-C source code
Provide QKQuerySet, a native Objective-C QuerySet
[Podspec] Remove swift sources

Makes no sense since CocoaPods doesn’t yet support Swift
[QKQuerySet] Introduce range to match QuerySet
Merge pull request #13 from kylef/objectivec

Add support for bridging to Objective-C