Add missing features in React 0.61.5

I'm hitting a few issues in attempting to build React 0.61.5 with PodToBUILD on the following archive:
'https://github.com/facebook/react-native/archive/v0.61.5.zip'

The following situations are occurring which make this tricky to handle
- Aliasing doesn't alias all subspecs, only the top level one. This requires manually aliasing right now.
- Header namespaces are mixed up for a child pod. For example, `RCTText` and `RCTImage`.
- There is a convention of importing pods into the Podfile _from_ a subspec? e.g. `pod 'React-Core/DevSupport', :path => "#{prefix}/"`