standalone mode, whiptail interface, userdefined classes and user customization

[insatomcat]

In order to add a standalone mode, we split the SEAPATH_HOST class into 2 :

• SEAPATH_HOST package_config will contain packages that are needed by all host installations, standalone or cluster node
• SEAPATH_CLUSTER will contain the packages needed for cluster mode.

We now need a way to have the user select more easily the classes he wants in his iso and the grub menu items he needs.

For that I propose a Text User Interface using whiptail (will work over ssh, docker, etc.). With this interface the user will be able to :

• choose the package classes he wants to download/have in the local mirror of the iso file (that way he can reduce the size of the iso file and the time it takes to build)
• choose the precise list of grub menu options he wants

He will need to call ./build_debian_iso with the "--custom" command line argument.
Not calling the argument will launch with defaults (all classes downloaded, and only one grub option with clustermode/lvmraid/english/no_debug/no_kerberos/no_cockpit)

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As a proof this will simplify the adding of classes, the second commit adds a class for german keyboard layout.

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Guest Disk config: rename vg1 to vg2

It can be useful to be able to mount the guest filesystem in the host (to check on disk usage for example, or to repair something). LVM will choke if we have 2 volume groups with the same name on the same system. To solve this, since the host will still use "vg1", we rename the guest VG to "vg2".

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Add the USERCUSTOMIZATION class to facilitate user configuration

This commits splits the base hierarchy into 3:

• srv_fai_config is still the default SEAPATH configuration
• usercustomization is the same hierarchy but git will not track it, and the user can put custom files in it
• build_tmp is a temporary folder where the installer will merge srv_fai_config and userconfiguration just before merging

srv_fai_config also includes now the new USERCUSTOMIZATION class, so that the files in the usercustomization/ folder can implement this class and override/add any setting.

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Allows userdefined classes

With this commit the user can add his own classes by:

• adding the class in the user_classes.conf file
• dealing with a numbered script in usercustomization/class/ folder (for example usercustomization/class/99-custom, chmod 755) to use the class
• adding all the files related to the classes in the usercustomization hierarchy