[Pod] Include subspec dependencies

Closes #62

No tests, because: https://github.com/CocoaPods/search.cocoapods.org/blob/trunk-database-rewrite/spec/lib/models/pod_spec.rb :scream: 
Can you maybe in a sentence explain what this code aims to achieve? For e.g. AFNetworking, how do users now find it, in addition to before? What text can they now enter that they couldn't before?