snf-deploy: Support Ganeti 2.10

..and later but NOT 2.8.

In Ganeti 2.10 --no-lvm-storage and --no-drbd-storage options of
gnt-cluster init are removed in favor of --enabled-disk-templates.

Additionally the packaging has changed. A valid ganeti installation
has: ganeti-haskell-2.10, ganeti-htools-2.10, ganeti-2.10,
snf-ganeti, ganeti2.

Since snf-ganeti (or ganeti) depends on all other we remove
ganeti-haskell and ganeti-htools from the REQUIRED_PACKAGES of
the Ganeti component. ganeti2 is a dummy transitional package that
satisfies external components dependencies (snf-image,
snf-cyclades-gtools, etc.)

The version to be installed is configurable in packages.conf.

Signed-off-by: Dimitris Aragiorgis <dimara@grnet.gr>
deploy/ci: Some changes wrt disk sizes

vcluster.conf:

  disk0_size is the size of base vcluster image to debootstrap
  disk1_size if the size of the extra disk to use for LVM

ganeti.conf:

  vg_size is the size of the VG to create if an extra disk is not
found

Ganeti has a hard requirement for VG more than 20480MB.

Signed-off-by: Dimitris Aragiorgis <dimara@grnet.gr>
deploy: Add missing decorators for ExtStorage

Signed-off-by: Dimitris Aragiorgis <dimara@grnet.gr>
deploy: Add configure scripts for Ganeti

Since we deploy Ganeti with packages, in order to be able
to run qa from source we should run configure with the
same options that debian builds the packages. Add new helper
scripts (configure-2.8 and configure-2.10) that do this
(for stable-2.8 and stable-2.10 respectively).

Signed-off-by: Dimitris Aragiorgis <dimara@grnet.gr>