Add support for Virtualbox Guest modules.
Fix linux-headers package name (depend on specific version).

Should be only temporary fix. We should add hook for installing guest
additions in target(s) that need support for virtualization.

Signed-off-by: Ville Korhonen <ville@xd.fi>
Enable X11 modules for VBox.
Move dev stuff to separate package list.

Moving development related packages to development.list.chroot. These
packages MUST NOT be included in stable/official versions.

Signed-off-by: Ville Korhonen <ville.korhonen@ylioppilastutkinto.fi>