Add NUI 0.5.2

Also, unless I'm missing something, I'm not able to push to CocoaPods/Specs like I use to be able to. I used to do a `git push`, but that fails now, and I see that the `Specs` Github team (which I belong to) only has read access.

When I try `pod push master NUI.podspec` and enter my credentials, I get the following:
```
error: The requested URL returned error: 403 while accessing https://github.com/CocoaPods/Specs.git/info/refs?service=git-receive-pack
fatal: HTTP request failed
```

Can someone help me with this? Thanks!