CocoaPods Podspec

Please can you update the podspec on cocoapods to version 2.3.

At the moment we have to define it in our podfile like this...

```
pod 'BSKeyboardControls', :git => 'https://github.com/simonbs/BSKeyboardControls.git' 
```

It would be great if we could just use it without specifying the github url like this:

```
pod 'BSKeyboardControls', '~> 2.3'
```

Thanks
