[!] Unable to add a source with url git@github.com:CocoaPods/Specs.git named master-1. You can try adding it manually in ~/.cocoapods/repos
I was getting the same error with only difference that there was different URL. I was trying to install private pods from private repository. What helped is to add ssh-key to profile.
ssh-key using this guide: https://help.github.com/articles/generating-a-new-ssh-key-and-adding-it-to-the-ssh-agent/. Hope this helps.