Specified license text in Podspec

I have taken the liberty to publish the Podspec to CocoaPods/Specs (https://github.com/CocoaPods/Specs/blob/master/MKNumberBadgeView/0.0.1/MKNumberBadgeView.podspec). However, it seems the spec won't lint without specifying `:text` at `license` due to a lack of `LICENSE` file in the repo.

FYR, CocoaPods/Specs#4426, CocoaPods/Specs#4496