add a default node for the trove-server role

fixes bnc#889345
Merge pull request #21 from mapleoin/default-node

add a default node for the trove-server role
set use_nova_server_config_drive to true

This allows nova file injection via config_drive to work which is needed
when trove adds configuration files to newly created instances via
cloud-init.
Merge pull request #22 from mapleoin/config_drive

set use_nova_server_config_drive to true