hostname.rb: allow restore on a blank config

should be a graceful no-op
qemu: do not hardcode -vga qxl -- TODO: config it!

Does qemu.org flavour (as opposed to linux-kvm.org one) support QXL?

TODO: make this configurable via the web interface.
dnsmasq: fix NoMethodError on empty domain name
qemu: fix Instance#paused?
qemu: fix regex: snaphost listing
dnsmasq: skip --host-record when version < 2.64
util: version_spec.rb
version_spec.rb more expressive
slightly improve version_spec.rb
correct required Dnsmasq version for --host-record
better Dnsmasq version handling
Still more info on Dnsmasq versions
Merge branch 'master' into margay