devgrid::compute: don't restart iptables

Many OpenStack services but nova-compute do something with iptables
rules, so we'd better not touch them here.

In particular, before this commit rules added by nova-api to provide
guests access to metadata service were missing in freshly-installed
system.

Change-Id: I9b2aaac15c3055178ff7ab514b89eaab938a9a50
Update: update to 1.1.2 with downgrading qemu

- means to downgrade QEMU to stock version;
- enable 'updates' repo for version-to-version upgrades.

Change-Id: I5465d2a454a0ac4a85188973b3ea9046d4f0c659