Do NOT create a 'null'-named application when user clicks Cancel button

git-svn-id: svn://svn.forge.objectweb.org/svnroot/contrail/trunk/conpaas@4906 ef35cc4a-2640-4bbf-98bc-65920db7d8ae
conpaas-docs: improvements to the installation guide

- Mention Wheezy official ec2 images
- Note that users need to provide a public hostname for the director
- Explain how to add users from the cli
- Update ec2 AMI-IDs


git-svn-id: svn://svn.forge.objectweb.org/svnroot/contrail/trunk/conpaas@4908 ef35cc4a-2640-4bbf-98bc-65920db7d8ae