title: pod name with url in podfile
body: <p>I see certain pod files mentioning the pods with just its name (pod 'podName') but certain pods along with its git url (pod 'podName' , :git => 'open source git url')... I also tend to have one such case where I got error when I mention the pod just by its name and without its git url..
  So what difference does it really make ? 
  "<em>pod 'podName'</em>" vs "<em>pod 'podName' , :git => 'open source git url'</em>" in pod file ?
  For certain pods if I just do a pod install with just the pod name that was just giving out some error which seems to be working only along with its git url. So when is that actually required to specify the git url and when not to ?</p>