Ticket #3027: use xorriso (if exists) for writing into ISO images

Signed-off-by: Slava Zanko <slavazanko@gmail.com>
Indentation and refactoring (regards to http://pubs.opengroup.org/onlinepubs/9699919799/idx/shell.html)

Signed-off-by: Slava Zanko <slavazanko@gmail.com>
fixup! Ticket #3027: use xorriso (if exists) for writing into ISO images
fixup! Ticket #3027: use xorriso (if exists) for writing into ISO images
Merge branch '3027_xorriso'

* 3027_xorriso:
  fixup! Ticket #3027: use xorriso (if exists) for writing into ISO images
  fixup! Ticket #3027: use xorriso (if exists) for writing into ISO images
  Indentation and refactoring (regards to http://pubs.opengroup.org/onlinepubs/9699919799/idx/shell.html)
  Ticket #3027: use xorriso (if exists) for writing into ISO images