Support adding custom packages

[vasquesbc]

it would be great to be able to add custom packages to "/System/Installation/Packages/" as described in as described in http://books.google.de/books?id=H3awpzaO7IwC&pg=PA248&lpg=PA248&dq=osinstall.collection+apple&source=bl&ots=_Vm12Yry7v&sig=K890ZjWVN7IyQ0MU5WZkzSa-n34&hl=de&sa=X&ei=5cscU864G8Sa4wTytoGACQ&ved=0CEkQ6AEwAg#v=onepage&q=osinstall.collection%20apple&f=false
it would be necessary to create an "OSInstall.collection" file as well - an example can be found here: https://github.com/jedi4ever/veewee/blob/master/templates/OSX/prepare_veewee_iso/support/OSInstall.collection

[ntkme]

Sorry. It won't be added now.

However, in 1.1.0 release, several new features were added to help you do further modification:

• -s --interactive-shell 🐚
  Open an interactive shell to edit InstallESD or BaseSystem

  You can do any modification in shell. Exit when you have finished editing.
  To open a Finder, type open . in the shell.

• --grow sectors
  Add extra space for additional stuff

  A sector is 512 bytes.

• --shrink
  Shrink to fit after merging DMG

[vasquesbc]

looks suitable to me.
i will have a look.
thank you!