gerrit change picker accepts extra changes

Use the --change CHANGEID to specify extra changes to be selected. You
can use the option multiple times as well.
Merge pull request #39 from matelakat/add-extra-changes

gerrit change picker accepts extra changes
Only include open changes

If extra changes are specified, only include them, if they are new ones.
Merge pull request #40 from matelakat/add-extra-changes

Only include open changes
Use bridge names for neutron builds

As neutron does not recognise the network name-label, we need to pass
the bridge name. This means, that we need to skip the specification of
FLAT_NETWORK_BRIDGE.

This way, the bridge name will be passed to domU.
Merge pull request #41 from matelakat/use-bridge-names

Use bridge names for neutron builds