title: Cannot clone github repository
body: <p>Based on this guide:
  <a href="https://github.com/cytoscape/cytoscape" rel="nofollow">https://github.com/cytoscape/cytoscape</a></p>
  
  <p>I am running a script on Ubuntu that clones a set of github repositories:
  <a href="https://github.com/cytoscape/cytoscape/blob/develop/cy.sh" rel="nofollow">https://github.com/cytoscape/cytoscape/blob/develop/cy.sh</a></p>
  
  <p>It fails with:</p>
  
  <pre><code>$ ./cy.sh init
  Target directory = 
  Cytoscape project will be cloned to: /home/user/projects/cytoscape
  Cloning: parent (URI = git@github.com:cytoscape/cytoscape-parent.git)
  Cloning into 'parent'...
  Permission denied (publickey).
  fatal: Could not read from remote repository.
  
  Please make sure you have the correct access rights
  and the repository exists.
  Could not clone remote repository: /home/user/projects/cytoscape
  </code></pre>
  
  <p>If I instead from command line do:</p>
  
  <pre><code>git clone https://github.com/cytoscape/cytoscape-parent.git
  </code></pre>
  
  <p>it works.</p>
  
  <p>on what systems does:</p>
  
  <pre><code>git clone git@github.com:cytoscape/cytoscape-parent.git
  </code></pre>
  
  <p>work?</p>