Updated photon-admin-guide doc

Change-Id: Ia3722affa7dc9548738a0553c59fc9ad99f3f10c
Reviewed-on: http://photon-jenkins.eng.vmware.com/1071
Reviewed-by: Divya Thaluru <[email protected]>
Tested-by: Divya Thaluru <[email protected]>

Updating the COPYING file.

* Updating COPYING file content
* Adding the COPYING file in the root directory of the iso

Change-Id: I4967ed08aae2dafb00e0558b0db56088c2930198
Reviewed-on: http://photon-jenkins.eng.vmware.com/747
Reviewed-by: Sharath George
Tested-by: Sharath George

fix regression in gpg key path for photon-extras repo

Change-Id: Ifae23fc9bdc71a3d7f7f942e0bf6835867b499d0
Reviewed-on: http://photon-jenkins.eng.vmware.com/733
Reviewed-by: Sharath George
Tested-by: Sharath George