title: Pod install, proxy issue
body: <p>I'm trying to run <strong>pod install</strong> in vain :</p>
  
  <pre><code>Analyzing dependencies
  Creating shallow clone of spec repo `master` from `https://github.com/CocoaPods/Specs.git`
  [!] Unable to add a source with url `https://github.com/CocoaPods/Specs.git` named `master`.
  You can try adding it manually in `~/.cocoapods/repos` or via `pod repo add`.
  </code></pre>
  
  <p>I think i have a proxy issue, but i don't know how to fix it. These is the result when i try <strong>pod setup</strong></p>
  
  <pre><code>Setting up CocoaPods master repo
  [!] /usr/bin/git clone https://github.com/CocoaPods/Specs.git master --depth=1
  
  Cloning into 'master'...
  
  fatal: unable to access 'https://github.com/CocoaPods/Specs.git/':Received HTTP code 503 from proxy after CONNECT
  </code></pre>