[Wish] Add support for Ubuntu Server

[Cubic PPA]

Cubic doesn't support Ubuntu Server.

[tim elston (timmah)]

+1 - Require support for custom server iso's

Currently get the error "Warning! you are in NOT the chroot environment. Exiting!"

[Joe Carey (indepndnt)]

Hi! The problem seems to be with Cubic's assumption that the squashed filesystem is in a folder named "casper". In the Ubuntu Server iso, the folder is named "install".

I posted an explanation of how I fixed the problem for myself here: https://askubuntu.com/a/1010733/800716

A good permanent solution might be to make `casper/` an editable parameter and check for the existence of the folder before continuing. The chroot command fails because the squashfs folder does not exist because the unsquashfs command couldn't find the source file.

[Doug Breshears (o-doug-5)]

I made changes to the utilites.py and transitions.py files for the following..

1) Change the default 'casper' directory name to a function call which determines the directory name.
2) Add initrd.gz possibility for server iso's
3) Check if filesystem.manifest-remove file exists before enumerating the contents.

This seems to work for me so I have included the patch file as a solution.

[Cubic PPA (cubic-wizard)]

Thanks Doug. I'll take a look at this.

[Cubic PPA (cubic-wizard)]

The fix for this bug is currently in the *Development* branch.

You can test it by doing the following:

    # Remove Cubic
    $ sudo apt autoremove --purge cubic

    # Remove the *Release* repository
    $ sudo apt-add-repository --remove ppa:cubic-wizard/release

    # Add the *Development* repository
    $ sudo add-apt-repository ppa:cubic-wizard/development

    # Install the *Development* version of Cubic
    $ sudo apt update
    $ sudo apt install cubic

[Cubic PPA (cubic-wizard)]

Fix released to "trunk" revision 112.
Fix released to "release" revision 24.